diff --git a/openfl/component/aggregator/aggregator.py b/openfl/component/aggregator/aggregator.py
index eaac9fa6a0..c64ae4a5f7 100644
--- a/openfl/component/aggregator/aggregator.py
+++ b/openfl/component/aggregator/aggregator.py
@@ -1,7 +1,6 @@
 # Copyright 2020-2024 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
-
 """Aggregator module."""
 
 import logging
@@ -20,6 +19,8 @@
 
 logger = logging.getLogger(__name__)
 
+VALID_MODES = {"train_and_validate", "evaluate"}
+
 
 class Aggregator:
     """An Aggregator is the central node in federated learning.
@@ -82,6 +83,7 @@ def __init__(
         log_memory_usage=False,
         write_logs=False,
         callbacks: Optional[List] = None,
+        mode: str = "train_and_validate",
     ):
         """Initializes the Aggregator.
 
@@ -108,7 +110,12 @@ def __init__(
                 Defaults to 1.
             initial_tensor_dict (dict, optional): Initial tensor dictionary.
             callbacks: List of callbacks to be used during the experiment.
+            mode (str, optional): Operation mode. Can be 'train_and_validate',
+                'evaluate'. Defaults to 'train_and_validate'.
         """
+        if mode not in VALID_MODES:
+            raise ValueError(f"Mode must be one of {VALID_MODES}, got {mode}")
+        self.mode = mode
         self.round_number = 0
 
         if single_col_cert_common_name:
@@ -208,9 +215,13 @@ def _load_initial_tensors(self):
             self.model, compression_pipeline=self.compression_pipeline
         )
 
-        if round_number > self.round_number:
+        # Check mode before updating round number
+        if self.mode == "evaluate":
+            logger.info(f"Skipping round_number check for mode {self.mode}")
+        elif round_number > self.round_number:
             logger.info(f"Starting training from round {round_number} of previously saved model")
             self.round_number = round_number
+
         tensor_key_dict = {
             TensorKey(k, self.uuid, self.round_number, False, ("model",)): v
             for k, v in tensor_dict.items()
diff --git a/openfl/interface/aggregator.py b/openfl/interface/aggregator.py
index 80ce56e32e..fd9246ad61 100644
--- a/openfl/interface/aggregator.py
+++ b/openfl/interface/aggregator.py
@@ -1,18 +1,34 @@
 # Copyright 2020-2024 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
-
 """Aggregator module."""
 
 import sys
 from logging import getLogger
 from pathlib import Path
 
-from click import Path as ClickPath
-from click import confirm, echo, group, option, pass_context, style
+from click import (
+    Choice,
+    confirm,
+    echo,
+    group,
+    option,
+    pass_context,
+    style,
+)
+from click import (
+    Path as ClickPath,
+)
 
 from openfl.cryptography.ca import sign_certificate
-from openfl.cryptography.io import get_csr_hash, read_crt, read_csr, read_key, write_crt, write_key
+from openfl.cryptography.io import (
+    get_csr_hash,
+    read_crt,
+    read_csr,
+    read_key,
+    write_crt,
+    write_key,
+)
 from openfl.cryptography.participant import generate_csr
 from openfl.federated import Plan
 from openfl.interface.cli_helper import CERT_DIR
@@ -52,9 +68,21 @@ def aggregator(context):
     default="plan/cols.yaml",
     type=ClickPath(exists=True),
 )
-def start_(plan, authorized_cols):
-    """Start the aggregator service."""
+@option(
+    "-m",
+    "--mode",
+    type=Choice(["train_and_validate", "evaluate"]),
+    default="train_and_validate",
+    help="Operation mode - either train_and_validate or evaluate",
+)
+def start_(plan, authorized_cols, mode):
+    """Start the aggregator service.
 
+    Args:
+        plan (str): Path to plan config file
+        authorized_cols (str): Path to authorized collaborators file
+        mode (str): Operation mode - either train_and_validate or evaluate
+    """
     if is_directory_traversal(plan):
         echo("Federated learning plan path is out of the openfl workspace scope.")
         sys.exit(1)
@@ -62,14 +90,21 @@ def start_(plan, authorized_cols):
         echo("Authorized collaborator list file path is out of the openfl workspace scope.")
         sys.exit(1)
 
-    plan = Plan.parse(
+    # Parse plan and override mode if specified
+    parsed_plan = Plan.parse(
         plan_config_path=Path(plan).absolute(),
         cols_config_path=Path(authorized_cols).absolute(),
     )
 
+    # Set mode in aggregator settings
+    if "settings" not in parsed_plan.config["aggregator"]:
+        parsed_plan.config["aggregator"]["settings"] = {}
+    parsed_plan.config["aggregator"]["settings"]["mode"] = mode
+    logger.info(f"Setting aggregator mode to: {mode}")
+
     logger.info("🧿 Starting the Aggregator Service.")
 
-    plan.get_server().serve()
+    parsed_plan.get_server().serve()
 
 
 @aggregator.command(name="generate-cert-request")