diff --git a/src/common_access_model/schema/common_access_model.yaml b/src/common_access_model/schema/common_access_model.yaml
index 61919d10..807c8c1e 100644
--- a/src/common_access_model/schema/common_access_model.yaml
+++ b/src/common_access_model/schema/common_access_model.yaml
@@ -673,6 +673,7 @@ classes:
       - description
       - do_id
       - file_id
+      - actual_number_of_participants
       - publication
         #TODO: Are these good elements for the core entity?
       - data_collection_start
diff --git a/tests/data/valid/Dataset-001.yaml b/tests/data/valid/Dataset-001.yaml
index b2195f95..c127d2cc 100644
--- a/tests/data/valid/Dataset-001.yaml
+++ b/tests/data/valid/Dataset-001.yaml
@@ -7,6 +7,7 @@ file_id:
 - dr-bpfgefc86h
 - dr-mabd0lfbmq
 - dr-njl7vp2sz9
+actual_number_of_participants: 5
 publication:
 - bibliographic_reference: Quack F, Meow N, Meow E, Meow A. Social behavior in goats is mostly unremarkable. Ann Hayloft Genet. 2017;24(12):283-289.
   external_id: