diff --git a/app/models/ect_at_school_period.rb b/app/models/ect_at_school_period.rb
index 7ba35a49..775664a3 100644
--- a/app/models/ect_at_school_period.rb
+++ b/app/models/ect_at_school_period.rb
@@ -15,6 +15,10 @@ class ECTAtSchoolPeriod < ApplicationRecord
             notify_email: true,
             allow_nil: true
 
+  validates :email,
+            email_uniqueness: true,
+            allow_nil: true
+
   validates :started_on,
             presence: true
 
diff --git a/db/migrate/20250120134632_add_unique_constraint_to_email.rb b/db/migrate/20250120134632_add_unique_constraint_to_email.rb
new file mode 100644
index 00000000..8456539f
--- /dev/null
+++ b/db/migrate/20250120134632_add_unique_constraint_to_email.rb
@@ -0,0 +1,6 @@
+class AddUniqueConstraintToEmail < ActiveRecord::Migration[8.0]
+  def change
+    add_index :ect_at_school_periods, :email, unique: true, where: "email IS NOT NULL", name: "unique_email_on_ect_at_school_periods"
+    add_index :mentor_at_school_periods, :email, unique: true, where: "email IS NOT NULL", name: "unique_email_on_mentor_at_school_periods"
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 54404c2e..4930d554 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_01_20_095631) do
+ActiveRecord::Schema[8.0].define(version: 2025_01_20_134632) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
   enable_extension "pg_trgm"
@@ -150,6 +150,7 @@
     t.enum "working_pattern", enum_type: "working_pattern"
     t.string "email"
     t.index "teacher_id, ((finished_on IS NULL))", name: "index_ect_at_school_periods_on_teacher_id_finished_on_IS_NULL", unique: true, where: "(finished_on IS NULL)"
+    t.index ["email"], name: "unique_email_on_ect_at_school_periods", unique: true, where: "(email IS NOT NULL)"
     t.index ["school_id", "teacher_id", "started_on"], name: "index_ect_at_school_periods_on_school_id_teacher_id_started_on", unique: true
     t.index ["school_id"], name: "index_ect_at_school_periods_on_school_id"
     t.index ["teacher_id", "started_on"], name: "index_ect_at_school_periods_on_teacher_id_started_on", unique: true
@@ -280,6 +281,7 @@
     t.uuid "legacy_end_id"
     t.string "email"
     t.index "school_id, teacher_id, ((finished_on IS NULL))", name: "idx_on_school_id_teacher_id_finished_on_IS_NULL_dd7ee16a28", unique: true, where: "(finished_on IS NULL)"
+    t.index ["email"], name: "unique_email_on_mentor_at_school_periods", unique: true, where: "(email IS NOT NULL)"
     t.index ["school_id", "teacher_id", "started_on"], name: "idx_on_school_id_teacher_id_started_on_17d46e7783", unique: true
     t.index ["school_id"], name: "index_mentor_at_school_periods_on_school_id"
     t.index ["teacher_id", "started_on"], name: "index_mentor_at_school_periods_on_teacher_id_started_on", unique: true