diff --git a/app/helpers/event_helper.rb b/app/helpers/event_helper.rb
index 25ac9f890a..92f4e8fdea 100644
--- a/app/helpers/event_helper.rb
+++ b/app/helpers/event_helper.rb
@@ -143,7 +143,7 @@ def resolve_answer_text(field, submitted_answer)
     case field&.field_identifier
     when *FormField::SECTOR_FIELD_IDENTIFIERS
       resolve.call(Sector)
-    when "primary_age_group", "additional_age_group"
+    when *FormField::AGE_GROUP_FIELD_IDENTIFIERS
       resolve.call(Category)
     else
       submitted_answer
diff --git a/app/models/form_field.rb b/app/models/form_field.rb
index 6b7c55d1cc..ff1619dcfe 100644
--- a/app/models/form_field.rb
+++ b/app/models/form_field.rb
@@ -37,15 +37,20 @@ class FormField < ApplicationRecord
   # (as a string). Maps the field identifier to its backing CategoryType name.
   DYNAMIC_FIELD_CATEGORY_TYPES = {
     "primary_age_group" => "AgeRange",
+    "additional_age_groups" => "AgeRange",
     "additional_age_group" => "AgeRange"
   }.freeze
 
   # The "primary" and "additional" age group fields. Both are backed by AgeRange
   # categories but omit the catch-all "Mixed-age groups" category — a respondent
   # names the concrete age groups they serve, not the mixed bucket.
+  #
+  # The "additional" field is multi-select, so its current identifier is plural;
+  # the legacy singular name is kept so existing form data keeps resolving
+  # (current name first, legacy last — matching the sector identifiers).
   PRIMARY_AGE_GROUP_FIELD_IDENTIFIER = "primary_age_group"
-  ADDITIONAL_AGE_GROUP_FIELD_IDENTIFIER = "additional_age_group"
-  AGE_GROUP_FIELD_IDENTIFIERS = [ PRIMARY_AGE_GROUP_FIELD_IDENTIFIER, ADDITIONAL_AGE_GROUP_FIELD_IDENTIFIER ].freeze
+  ADDITIONAL_AGE_GROUP_FIELD_IDENTIFIERS = %w[additional_age_groups additional_age_group].freeze
+  AGE_GROUP_FIELD_IDENTIFIERS = [ PRIMARY_AGE_GROUP_FIELD_IDENTIFIER, *ADDITIONAL_AGE_GROUP_FIELD_IDENTIFIERS ].freeze
 
   # The payment-method field. Its answer options ("Credit card (now)", etc.) are
   # wired to Stripe charge logic in the controllers, so they must not be edited
diff --git a/app/models/person.rb b/app/models/person.rb
index 424dd07d15..d600ac8123 100644
--- a/app/models/person.rb
+++ b/app/models/person.rb
@@ -229,8 +229,9 @@ def remote_search_label
   end
 
   # Field identifiers whose "Other" free text maps onto the category-backed
-  # profile fields shown on the edit page.
-  OTHER_WORKSHOP_SETTING_IDENTIFIERS = %w[primary_age_group additional_age_group].freeze
+  # profile fields shown on the edit page. Mirrors the age group fields (current
+  # plural + legacy singular) so both keep resolving.
+  OTHER_WORKSHOP_SETTING_IDENTIFIERS = FormField::AGE_GROUP_FIELD_IDENTIFIERS
 
   # Free-text "Other" sectors the person typed on registration forms.
   # They can't be Sector records, so they're surfaced beside the sector tags.
diff --git a/app/services/event_registration_services/public_registration.rb b/app/services/event_registration_services/public_registration.rb
index ff7c3e3e82..dd00ad22d2 100644
--- a/app/services/event_registration_services/public_registration.rb
+++ b/app/services/event_registration_services/public_registration.rb
@@ -276,7 +276,7 @@ def assign_tags(person, organization)
       primary_sector_ids = collect_sector_ids(FormField::PRIMARY_SECTOR_FIELD_IDENTIFIERS)
       additional_sector_ids = collect_sector_ids(FormField::ADDITIONAL_SECTOR_FIELD_IDENTIFIERS)
       primary_age_ids = collect_ids_from_checkboxes("primary_age_group")
-      additional_age_ids = collect_ids_from_checkboxes("additional_age_group")
+      additional_age_ids = FormField::ADDITIONAL_AGE_GROUP_FIELD_IDENTIFIERS.flat_map { |id| collect_ids_from_checkboxes(id) }
 
       if primary_sector_ids.any? || additional_sector_ids.any?
         person.tag_sectors(primary_ids: primary_sector_ids, additional_ids: additional_sector_ids)
diff --git a/app/services/form_builder_service.rb b/app/services/form_builder_service.rb
index daa33f5721..49928c9b00 100644
--- a/app/services/form_builder_service.rb
+++ b/app/services/form_builder_service.rb
@@ -49,7 +49,7 @@ def call
       agency_street agency_city agency_state agency_zip agency_country
     ],
     person_background: %w[racial_ethnic_identity],
-    professional_info: %w[primary_sector_single additional_sectors primary_age_group additional_age_group],
+    professional_info: %w[primary_sector_single additional_sectors primary_age_group additional_age_groups],
     marketing: %w[referral_source training_motivation interested_in_more],
     scholarship: %w[scholarship_eligibility scholarship_contribution impact_description implementation_plan additional_comments],
     payment: %w[payment_method],
@@ -86,7 +86,7 @@ def call
       "Organization Country"
     ],
     person_background: [ "How would you best describe yourself?" ],
-    professional_info: [ "Primary sector", "Additional sectors", "Primary Age Group(s) Served", "Additional Age Group(s) Served" ],
+    professional_info: [ "Primary sector", "Additional sectors", "Primary age group served", "Additional age groups served" ],
     marketing: [
       "How did you hear about this AWBW training?",
       "What motivated you to sign up for AWBW's Facilitator Training?",
@@ -450,11 +450,11 @@ def build_professional_info_fields(form, position)
     position = add_field(form, position, "Additional sectors", :multi_select_checkbox,
                          key: "additional_sectors", group: "professional", required: false,
                          subtitle: "Select all options that represent who you intend to serve through the art workshops (check all that apply)")
-    position = add_field(form, position, "Primary Age Group(s) Served", :single_select_dropdown,
+    position = add_field(form, position, "Primary age group served", :single_select_dropdown,
                          key: "primary_age_group", group: "professional", required: false,
                          subtitle: "Select the age group you primarily intend to serve through the art workshops")
-    position = add_field(form, position, "Additional Age Group(s) Served", :multi_select_checkbox,
-                         key: "additional_age_group", group: "professional", required: false,
+    position = add_field(form, position, "Additional age groups served", :multi_select_checkbox,
+                         key: "additional_age_groups", group: "professional", required: false,
                          subtitle: "Select all additional age groups you may serve through the art workshops (check all that apply)")
     position
   end
diff --git a/spec/models/form_field_spec.rb b/spec/models/form_field_spec.rb
index 51a44c9e50..79307a81c5 100644
--- a/spec/models/form_field_spec.rb
+++ b/spec/models/form_field_spec.rb
@@ -445,12 +445,20 @@ def selectable_field(type:, option_names:)
         type = create(:category_type, name: "AgeRange")
         concrete = create(:category, :published, category_type: type, name: "3-5")
         mixed = create(:category, :published, category_type: type, name: Category::MIXED_AGE_RANGE_NAME)
-        field = create(:form_field, form: form, answer_type: :multi_select_checkbox, field_identifier: "additional_age_group")
+        field = create(:form_field, form: form, answer_type: :multi_select_checkbox, field_identifier: "additional_age_groups")
 
         expect(field.dynamic_categories).to eq([ concrete ])
         expect(field.answer_inclusion_error([ concrete.id.to_s ])).to be_nil
         expect(field.answer_inclusion_error([ mixed.id.to_s ])).to eq("has an invalid selection")
       end
+
+      it "still resolves the legacy singular additional_age_group identifier" do
+        type = create(:category_type, name: "AgeRange")
+        concrete = create(:category, :published, category_type: type, name: "3-5")
+        field = create(:form_field, form: form, answer_type: :multi_select_checkbox, field_identifier: "additional_age_group")
+
+        expect(field.dynamic_categories).to eq([ concrete ])
+      end
     end
   end
 
diff --git a/spec/services/event_registration_services/public_registration_spec.rb b/spec/services/event_registration_services/public_registration_spec.rb
index 7f9eb316a2..629237c75e 100644
--- a/spec/services/event_registration_services/public_registration_spec.rb
+++ b/spec/services/event_registration_services/public_registration_spec.rb
@@ -185,7 +185,7 @@ def register_with(position:)
         form: form,
         form_params: base_form_params(first_name: "Al", last_name: "Ng", email: "al@example.com").merge(
           field_id("primary_age_group") => [ young.id.to_s ],
-          field_id("additional_age_group") => [ teen.id.to_s ]
+          field_id("additional_age_groups") => [ teen.id.to_s ]
         )
       )
 
diff --git a/spec/services/form_builder_service_spec.rb b/spec/services/form_builder_service_spec.rb
index b6717e268c..bd7fc439a5 100644
--- a/spec/services/form_builder_service_spec.rb
+++ b/spec/services/form_builder_service_spec.rb
@@ -153,7 +153,7 @@
 
       it "asks for a single primary age group via a dropdown alongside additional-age checkboxes" do
         primary = form.form_fields.find_by(field_identifier: "primary_age_group")
-        additional = form.form_fields.find_by(field_identifier: "additional_age_group")
+        additional = form.form_fields.find_by(field_identifier: "additional_age_groups")
 
         expect(primary.answer_type).to eq("single_select_dropdown")
         expect(additional.answer_type).to eq("multi_select_checkbox")
diff --git a/spec/system/public_registration_form_submission_spec.rb b/spec/system/public_registration_form_submission_spec.rb
index ac7c04f389..2a7b75726c 100644
--- a/spec/system/public_registration_form_submission_spec.rb
+++ b/spec/system/public_registration_form_submission_spec.rb
@@ -101,7 +101,7 @@
         "primary_sector_single" => sector_education.id.to_s,
         "additional_sectors" => sector_mental_health.id.to_s,
         "primary_age_group" => age_adults.id.to_s,
-        "additional_age_group" => age_teens.id.to_s,
+        "additional_age_groups" => age_teens.id.to_s,
         "racial_ethnic_identity" => "Multi-racial",
         "referral_source" => "Online Search",
         "training_motivation" => "Address staff burnout through art",
@@ -393,7 +393,7 @@ def fill_full_registration
     select_pr reg_field("primary_sector_single"), "Education"
     check_pr_box reg_field("additional_sectors"), sector_mental_health.id.to_s
     select_pr reg_field("primary_age_group"), "Adults (18+)"
-    check_pr_box reg_field("additional_age_group"), age_teens.id.to_s
+    check_pr_box reg_field("additional_age_groups"), age_teens.id.to_s
 
     choose_pr_radio reg_field("racial_ethnic_identity"), "Multi-racial"
     choose_pr_radio reg_field("referral_source"), "Online Search"