diff --git a/DESCRIPTION b/DESCRIPTION
index 3bda659..3e1abd7 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -7,7 +7,8 @@ Authors@R: c(
   )
 Description: Helper functions to work with spreadsheets and the "A1:D10" style
     of cell range specification.
-Depends: R (>= 3.0.0)
+Depends:
+    R (>= 3.0.0)
 License: MIT + file LICENSE
 LazyData: true
 URL: https://github.com/jennybc/cellranger
@@ -15,3 +16,4 @@ BugReports: https://github.com/jennybc/cellranger/issues
 Suggests:
     covr,
     testthat
+RoxygenNote: 5.0.1.9000
diff --git a/NAMESPACE b/NAMESPACE
index 4e76b34..9cb1b85 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -1,4 +1,4 @@
-# Generated by roxygen2 (4.1.1): do not edit by hand
+# Generated by roxygen2: do not edit by hand
 
 S3method(as.cell_limits,"NULL")
 S3method(as.cell_limits,cell_limits)
diff --git a/R/cell-limits.R b/R/cell-limits.R
index 6d18d93..6d84ef4 100644
--- a/R/cell-limits.R
+++ b/R/cell-limits.R
@@ -5,13 +5,15 @@
 #' operations on a spreadsheet. Downstream code can be written assuming cell
 #' limits are stored in a valid \code{cell_limits} object.
 #'
-#' A \code{cell_limits} object is a list with two components:
+#' A \code{cell_limits} object is a list with three components:
 #'
 #' \itemize{
 #'   \item \code{ul} vector specifying upper left cell of target rectangle, of
 #'   the form \code{c(ROW_MIN, COL_MIN)}
 #'   \item \code{lr} vector specifying lower right cell of target rectangle, of
 #'   the form \code{c(ROW_MAX, COL_MAX)}
+#'   \item \code{wsn} string specifying worksheet name, which may be \code{NA},
+#'   meaning it's unspecified
 #' }
 #'
 #' This follows the spreadsheet convention where a cell range is described as
@@ -29,6 +31,7 @@
 #'
 #' @param ul vector identifying upper left cell of target rectangle
 #' @param lr vector identifying lower right cell of target rectangle
+#' @param wsn string containing worksheet name, optional
 #' @param x input to convert into a \code{cell_limits} object
 #'
 #' @return a \code{cell_limits} object
@@ -39,13 +42,17 @@
 #' cell_limits(c(NA, 7))
 #' cell_limits(lr = c(3, 7))
 #'
+#' cell_limits(c(1, 3), c(1, 5), "Sheet1")
+#' cell_limits(c(1, 3), c(1, 5), "Spaces are evil")
+#'
 #' dim(as.cell_limits("A1:F10"))
 #'
 #' @export
 cell_limits <- function(ul = c(NA_integer_, NA_integer_),
-                        lr = c(NA_integer_, NA_integer_)) {
+                        lr = c(NA_integer_, NA_integer_),
+                        wsn = NA_character_) {
 
-  stopifnot(length(ul) == 2L, length(lr) == 2L)
+  stopifnot(length(ul) == 2L, length(lr) == 2L, length(wsn) == 1L)
 
   ul <- as.integer(ul)
   lr <- as.integer(lr)
@@ -54,16 +61,16 @@ cell_limits <- function(ul = c(NA_integer_, NA_integer_),
   stopifnot(all(NA_or_pos(ul)))
   stopifnot(all(NA_or_pos(lr)))
 
-  if(is.na(ul[1]) && !is.na(lr[1])) ul[1] <- 1L
-  if(is.na(ul[2]) && !is.na(lr[2])) ul[2] <- 1L
+  if (is.na(ul[1]) && !is.na(lr[1])) ul[1] <- 1L
+  if (is.na(ul[2]) && !is.na(lr[2])) ul[2] <- 1L
 
   rows <- c(ul[1], lr[1])
   cols <- c(ul[2], lr[2])
 
-  if(!anyNA(rows)) stopifnot(rows[1] <= rows[2])
-  if(!anyNA(cols)) stopifnot(cols[1] <= cols[2])
+  if (!anyNA(rows)) stopifnot(rows[1] <= rows[2])
+  if (!anyNA(cols)) stopifnot(cols[1] <= cols[2])
 
-  structure(list(ul = ul, lr = lr),
+  structure(list(ul = ul, lr = lr, wsn = wsn),
             class = c("cell_limits", "list"))
 
 }
@@ -72,9 +79,10 @@ cell_limits <- function(ul = c(NA_integer_, NA_integer_),
 print.cell_limits <- function(x, ...) {
   ul <- ifelse(is.na(x$ul), "-", as.character(x$ul))
   lr <- ifelse(is.na(x$lr), "-", as.character(x$lr))
+  wsn <- if (is.na(x$wsn)) "" else paste0(" in '", x$wsn, "'")
 
   cat("<cell_limits (", ul[1], ", ", ul[2], ") x (",
-      lr[1], ", ", lr[2], ")>\n",
+      lr[1], ", ", lr[2], ")", wsn, ">\n",
       sep = "")
 }
 
@@ -101,6 +109,8 @@ as.cell_limits.NULL <- function(x) cell_limits()
 #' as.cell_limits("A1:D8")
 #' as.cell_limits("R5C11")
 #' as.cell_limits("R2C3:R6C9")
+#' as.cell_limits("Sheet1!R2C3:R6C9")
+#' as.cell_limits("'Spaces are evil'!R2C3:R6C9")
 #'
 #' @export
 as.cell_limits.character <- function(x) {
@@ -108,30 +118,34 @@ as.cell_limits.character <- function(x) {
   stopifnot(length(x) == 1L)
   x_orig <- x
 
-  x <- rm_dollar_signs(x)
-
-  y <- unlist(strsplit(x, ":"))
-  stopifnot(length(y) %in% 1:2)
+  y <- unlist(strsplit(x, "!"))
+  wsn <- if (length(y) > 1) y[[1]] else NA_character_
+  wsn <- remove_single_quotes(wsn)
+  raw_rg <- y[[length(y)]]
+  raw_rg <- rm_dollar_signs(raw_rg)
 
-  y <- rep_len(y[!grepl("\\s+", y)], 2)
+  rg <- unlist(strsplit(raw_rg, ":"))
+  stopifnot(length(rg) %in% 1:2)
+  rg <- rep_len(rg[!grepl("\\s+", rg)], 2)
 
   RC_regex <- "^R([0-9]+)C([0-9]+$)"
   A1_regex <- "^[A-Za-z]{1,3}[0-9]+$"
 
-  if(all(grepl(A1_regex, y))) {
-    y <- A1_to_RC(y)
-  } else if(!all(grepl(RC_regex, y))) {
+  if (all(grepl(A1_regex, rg))) {
+    rg <- A1_to_RC(rg)
+  } else if (!all(grepl(RC_regex, rg))) {
     stop("Trying to set cell limits, but requested range is invalid:\n",
-      x_orig)
+         x_orig)
   }
 
-  m <- regexec("^R([0-9]+)C([0-9]+$)", y)
-  m2 <- regmatches(y, m)
+  m <- regexec("^R([0-9]+)C([0-9]+$)", rg)
+  m2 <- regmatches(rg, m)
 
   jfun <- function(x) as.integer(x[2:3])
   cell_limits(
     jfun(m2[[1]]),
-    jfun(m2[[2]])
+    jfun(m2[[2]]),
+    wsn
   )
 }
 
@@ -140,6 +154,8 @@ as.cell_limits.character <- function(x) {
 #'
 #' @param x a cell_limits object
 #' @param RC logical, requesting "R1C1" positioning notation
+#' @param wsn logical, specifying whether worksheet name should be prepended to
+#'   the range, e.g. \code{Sheet1!A1:D4}
 #'
 #' @return length one character vector holding a cell range, in either A1 or
 #'   R1C1 positioning notation
@@ -149,19 +165,26 @@ as.cell_limits.character <- function(x) {
 #' as.range(rgCL)
 #' as.range(rgCL, RC = TRUE)
 #'
+#' rgCL_ws <- cell_limits(ul = c(1, 2), lr = c(7, 6), wsn = "A Sheet")
+#' as.range(rgCL_ws)
+#' as.range(rgCL_ws, RC = TRUE, wsn = TRUE)
+#'
 #' @export
-as.range <- function(x, RC = FALSE) {
+as.range <- function(x, RC = FALSE, wsn = FALSE) {
 
-  stopifnot(inherits(x, "cell_limits"))
+  stopifnot(inherits(x, "cell_limits"),
+            isTOGGLE(RC), isTOGGLE(wsn))
 
-  if(any(is.na(unlist(x)))) return(NA_character_)
+  if (anyNA(unlist(x[c("ul", "lr")]))) return(NA_character_)
 
-  range <- c(paste0("R", x$ul[1], "C", x$ul[2]),
-             paste0("R", x$lr[1], "C", x$lr[2]))
-
-  if(!RC) {
+  range <- c(row_col_to_RC(x$ul), row_col_to_RC(x$lr))
+  if (!RC) {
     range <- RC_to_A1(range)
   }
+  range <- paste(range, collapse = ":")
 
-  paste(range, collapse = ":")
+  if (wsn && !is.na(x$wsn)) {
+    range <- paste(add_single_quotes(x$wsn), range, sep = "!")
+  }
+  range
 }
diff --git a/R/row-col-to-from-RC.R b/R/row-col-to-from-RC.R
new file mode 100644
index 0000000..f5f91a0
--- /dev/null
+++ b/R/row-col-to-from-RC.R
@@ -0,0 +1 @@
+row_col_to_RC <- function(x) paste0("R", x[1], "C", x[2])
diff --git a/R/utils.R b/R/utils.R
index 6328c77..c672908 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -1,6 +1,14 @@
 rm_dollar_signs <- function(x) gsub('$', '', x, fixed = TRUE)
 
-char0_to_NA <- function(x) if(length(x) < 1) NA_character_ else x
+char0_to_NA <- function(x) if (length(x) < 1) NA_character_ else x
 
 isTOGGLE <- function(x) is.null(x) || isTRUE(x) || identical(x, FALSE)
 
+add_single_quotes <- function(x) {
+  if (grepl("\\s+", x)) {
+    x <- paste0("'", x, "'")
+  }
+  x
+}
+
+remove_single_quotes <- function(x) gsub("^'|'$", "", x)
diff --git a/man/A1_to_RC.Rd b/man/A1_to_RC.Rd
index 33bef2d..4f20057 100644
--- a/man/A1_to_RC.Rd
+++ b/man/A1_to_RC.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/A1-to-from-RC.R
 \name{A1_to_RC}
 \alias{A1_to_RC}
@@ -22,5 +22,6 @@ A1_to_RC("AZ10")
 A1_to_RC("AZ$10")
 A1_to_RC(c("A1", "AZ10"))
 A1_to_RC(c("", NA, "Q0"))
+
 }
 
diff --git a/man/RC_to_A1.Rd b/man/RC_to_A1.Rd
index fee5b18..75a4da7 100644
--- a/man/RC_to_A1.Rd
+++ b/man/RC_to_A1.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/A1-to-from-RC.R
 \name{RC_to_A1}
 \alias{RC_to_A1}
@@ -20,5 +20,6 @@ RC_to_A1("R1C1")
 RC_to_A1("R10C52")
 RC_to_A1(c("R1C1", "R10C52"))
 RC_to_A1(c("", NA, "R0C0"))
+
 }
 
diff --git a/man/anchored.Rd b/man/anchored.Rd
index 0deaae8..fdda005 100644
--- a/man/anchored.Rd
+++ b/man/anchored.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/anchor.R
 \name{anchored}
 \alias{anchored}
@@ -22,7 +22,7 @@ column or variable names of a two-dimensional input; if omitted, will be
 determined by checking whether \code{input} has column names}
 
 \item{byrow}{logical, indicating whether a one-dimensional input should run
-  down or to the right}
+down or to the right}
 }
 \value{
 a \code{\link{cell_limits}} object
@@ -70,5 +70,6 @@ dim(anchored(input = input))
 anchored(input = input, byrow = TRUE)
 as.range(anchored(input = input, byrow = TRUE), RC = TRUE)
 dim(anchored(input = input, byrow = TRUE))
+
 }
 
diff --git a/man/as.range.Rd b/man/as.range.Rd
index 6aefac6..d32ae6a 100644
--- a/man/as.range.Rd
+++ b/man/as.range.Rd
@@ -1,15 +1,18 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/cell-limits.R
 \name{as.range}
 \alias{as.range}
 \title{Convert a cell_limits object to a cell range}
 \usage{
-as.range(x, RC = FALSE)
+as.range(x, RC = FALSE, wsn = FALSE)
 }
 \arguments{
 \item{x}{a cell_limits object}
 
 \item{RC}{logical, requesting "R1C1" positioning notation}
+
+\item{wsn}{logical, specifying whether worksheet name should be prepended to
+the range, e.g. \code{Sheet1!A1:D4}}
 }
 \value{
 length one character vector holding a cell range, in either A1 or
@@ -22,5 +25,10 @@ Convert a cell_limits object to a cell range
 rgCL <- cell_limits(ul = c(1, 2), lr = c(7, 6))
 as.range(rgCL)
 as.range(rgCL, RC = TRUE)
+
+rgCL_ws <- cell_limits(ul = c(1, 2), lr = c(7, 6), wsn = "A Sheet")
+as.range(rgCL_ws)
+as.range(rgCL_ws, RC = TRUE, wsn = TRUE)
+
 }
 
diff --git a/man/cell_cols.Rd b/man/cell_cols.Rd
index 6e8f067..1c25c92 100644
--- a/man/cell_cols.Rd
+++ b/man/cell_cols.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/cell-rows-cell-cols.R
 \name{cell_cols}
 \alias{cell_cols}
@@ -8,7 +8,7 @@ cell_cols(x)
 }
 \arguments{
 \item{x}{vector of column limits; if character, converted to numeric; if
-  length greater than two, min and max will be taken with \code{NA.rm = TRUE}}
+length greater than two, min and max will be taken with \code{NA.rm = TRUE}}
 }
 \value{
 a \code{\link{cell_limits}} object
@@ -31,5 +31,6 @@ cell_cols(c(3, NA, 10))
 cell_cols("C:G")
 cell_cols(c("B", NA))
 cell_cols(LETTERS)
+
 }
 
diff --git a/man/cell_limits.Rd b/man/cell_limits.Rd
index 15ef96d..3d9cf98 100644
--- a/man/cell_limits.Rd
+++ b/man/cell_limits.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/cell-limits.R
 \name{cell_limits}
 \alias{as.cell_limits}
@@ -10,7 +10,7 @@
 \title{Create a cell_limits object}
 \usage{
 cell_limits(ul = c(NA_integer_, NA_integer_), lr = c(NA_integer_,
-  NA_integer_))
+  NA_integer_), wsn = NA_character_)
 
 \method{dim}{cell_limits}(x)
 
@@ -27,6 +27,8 @@ as.cell_limits(x)
 
 \item{lr}{vector identifying lower right cell of target rectangle}
 
+\item{wsn}{string containing worksheet name, optional}
+
 \item{x}{input to convert into a \code{cell_limits} object}
 }
 \value{
@@ -39,13 +41,15 @@ operations on a spreadsheet. Downstream code can be written assuming cell
 limits are stored in a valid \code{cell_limits} object.
 }
 \details{
-A \code{cell_limits} object is a list with two components:
+A \code{cell_limits} object is a list with three components:
 
 \itemize{
   \item \code{ul} vector specifying upper left cell of target rectangle, of
   the form \code{c(ROW_MIN, COL_MIN)}
   \item \code{lr} vector specifying lower right cell of target rectangle, of
   the form \code{c(ROW_MAX, COL_MAX)}
+  \item \code{wsn} string specifying worksheet name, which may be \code{NA},
+  meaning it's unspecified
 }
 
 This follows the spreadsheet convention where a cell range is described as
@@ -67,11 +71,18 @@ cell_limits(c(NA, 7), c(3, NA))
 cell_limits(c(NA, 7))
 cell_limits(lr = c(3, 7))
 
+cell_limits(c(1, 3), c(1, 5), "Sheet1")
+cell_limits(c(1, 3), c(1, 5), "Spaces are evil")
+
 dim(as.cell_limits("A1:F10"))
+
 as.cell_limits("A1")
 as.cell_limits("Q24")
 as.cell_limits("A1:D8")
 as.cell_limits("R5C11")
 as.cell_limits("R2C3:R6C9")
+as.cell_limits("Sheet1!R2C3:R6C9")
+as.cell_limits("'Spaces are evil'!R2C3:R6C9")
+
 }
 
diff --git a/man/cell_rows.Rd b/man/cell_rows.Rd
index b327680..1793fa6 100644
--- a/man/cell_rows.Rd
+++ b/man/cell_rows.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/cell-rows-cell-cols.R
 \name{cell_rows}
 \alias{cell_rows}
@@ -8,7 +8,7 @@ cell_rows(x)
 }
 \arguments{
 \item{x}{numeric vector of row limits; if length greater than two, min and
-  max will be taken with \code{NA.rm = TRUE}}
+max will be taken with \code{NA.rm = TRUE}}
 }
 \value{
 a \code{\link{cell_limits}} object
@@ -28,5 +28,6 @@ cell_rows(4:16)
 cell_rows(c(3, NA, 10))
 
 dim(cell_rows(1:5))
+
 }
 
diff --git a/man/cellranger.Rd b/man/cellranger.Rd
index 0566f8a..2ca390d 100644
--- a/man/cellranger.Rd
+++ b/man/cellranger.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/cellranger-package.r
 \docType{package}
 \name{cellranger}
diff --git a/man/letter_to_num.Rd b/man/letter_to_num.Rd
index b1ed504..15a2e57 100644
--- a/man/letter_to_num.Rd
+++ b/man/letter_to_num.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/A1-to-from-RC.R
 \name{letter_to_num}
 \alias{letter_to_num}
@@ -19,5 +19,6 @@ Convert column IDs from letter representation to integer
 letter_to_num('Z')
 letter_to_num(c('AA', 'ZZ', 'ABD', 'ZZZ'))
 letter_to_num(c(NA, ''))
+
 }
 
diff --git a/man/num_to_letter.Rd b/man/num_to_letter.Rd
index 00d6208..c5e266d 100644
--- a/man/num_to_letter.Rd
+++ b/man/num_to_letter.Rd
@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/A1-to-from-RC.R
 \name{num_to_letter}
 \alias{num_to_letter}
@@ -21,5 +21,6 @@ num_to_letter(900)
 num_to_letter(18278)
 num_to_letter(c(25, 52, 900, 18278))
 num_to_letter(c(NA, 0, 4.8, -4))
+
 }
 
diff --git a/tests/testthat/test-cell-specification.R b/tests/testthat/test-cell-specification.R
index 6724e32..a38aeea 100644
--- a/tests/testthat/test-cell-specification.R
+++ b/tests/testthat/test-cell-specification.R
@@ -69,6 +69,15 @@ test_that("Cell range is converted to a cell_limit object and vice versa", {
   expect_equal(as.range(rgCL), rgA1)
   expect_equal(as.range(rgCL, RC = TRUE), rgRC)
 
+  rgA1sheet <- "sheet!A1:C4"
+  rgRCsheet <- "sheet!R1C1:R4C3"
+  rgCLwsn <- cell_limits(ul = c(1, 1), lr = c(4, 3), wsn = "sheet")
+  expect_equal(as.cell_limits(rgA1sheet), rgCLwsn)
+  expect_equal(as.cell_limits(rgRCsheet), rgCLwsn)
+  expect_equal(as.range(rgCLwsn), rgA1)
+  expect_equal(as.range(rgCLwsn, RC = TRUE), rgRC)
+  expect_equal(as.range(rgCLwsn, RC = TRUE, wsn = TRUE), rgRCsheet)
+
   rgA1 <- "E7"
   rgA1A1 <- "E7:E7"
   rgRC <- "R7C5"
@@ -81,11 +90,29 @@ test_that("Cell range is converted to a cell_limit object and vice versa", {
   expect_equal(as.range(rgCL), rgA1A1)
   expect_equal(as.range(rgCL, RC = TRUE), rgRCRC)
 
+  rgA1sheet <- "sheet!E7"
+  rgA1A1sheet <- "sheet!E7:E7"
+  rgRCsheet <- "sheet!R7C5"
+  rgRCRCsheet <- "sheet!R7C5:R7C5"
+  rgCLsheet <- cell_limits(ul = c(7, 5), lr = c(7, 5), wsn = "sheet")
+  expect_equal(as.cell_limits(rgA1sheet), rgCLsheet)
+  expect_equal(as.cell_limits(rgRCsheet), rgCLsheet)
+  expect_equal(as.cell_limits(rgA1A1sheet), rgCLsheet)
+  expect_equal(as.cell_limits(rgRCRCsheet), rgCLsheet)
+  expect_equal(as.range(rgCLsheet, wsn = TRUE), rgA1A1sheet)
+  expect_equal(as.range(rgCLsheet, RC = TRUE, wsn = TRUE), rgRCRCsheet)
+
   rgCL <- cell_limits(ul = c(NA, 1), lr = c(4, NA))
   expect_true(is.na(as.range(rgCL)))
 
 })
 
+test_that("Whitespace-contained sheet names gain/lose single quotes", {
+  x <- cell_limits(ul = c(1, 1), lr = c(4, 3), wsn = "aaa bbb")
+  expect_identical(as.range(x, wsn = TRUE), "'aaa bbb'!A1:C4")
+  expect_identical(as.cell_limits("'aaa bbb'!A1:C4"), x)
+})
+
 test_that("Bad cell ranges throw errors", {
 
   expect_error(as.cell_limits("eggplant"))
@@ -162,6 +189,8 @@ test_that("Print method works", {
 
   expect_output(print(cell_limits(c(NA, 7), c(3, NA))),
                 "<cell_limits (1, 7) x (3, -)>", fixed = TRUE)
+  expect_output(print(cell_limits(c(NA, 7), c(3, NA), "a sheet")),
+                "<cell_limits (1, 7) x (3, -) in 'a sheet'>", fixed = TRUE)
 
 })