diff --git a/backend/app.py b/backend/app.py
index f451a9a..a054a6b 100644
--- a/backend/app.py
+++ b/backend/app.py
@@ -40,7 +40,7 @@ from .data_loader import (
 from .data_loader import get_data_info as get_db_info
 from . import flags
 from .places import build_place_index, build_place_registry, places_for_urn
-from .schemas import METRIC_DEFINITIONS, PHASE_GROUPS, RANKING_COLUMNS, SCHOOL_COLUMNS
+from .schemas import METRIC_DEFINITIONS, PHASE_GROUPS, PHASE_ORDER, RANKING_COLUMNS, SCHOOL_COLUMNS
 from .school_groups import (
     FAITH_GROUPS,
     FAITH_KEYS,
@@ -381,6 +381,12 @@ def clean_filter_values(series: pd.Series) -> list[str]:
     )
 
 
+def order_phases(phases: list[str]) -> list[str]:
+    """Phases in the order a child meets them; any GIAS adds later follow, A-Z."""
+    rank = {p: i for i, p in enumerate(PHASE_ORDER)}
+    return sorted(phases, key=lambda p: (rank.get(p.lower(), len(rank)), p))
+
+
 # =============================================================================
 # SECURITY MIDDLEWARE & HELPERS
 # =============================================================================
@@ -937,7 +943,7 @@ async def get_schools(
     result_filters = {
         "local_authorities": clean_filter_values(schools_df["local_authority"]) if "local_authority" in schools_df.columns else [],
         "school_types": clean_filter_values(schools_df["school_type"]) if "school_type" in schools_df.columns else [],
-        "phases": clean_filter_values(schools_df["phase"]) if "phase" in schools_df.columns else [],
+        "phases": order_phases(clean_filter_values(schools_df["phase"])) if "phase" in schools_df.columns else [],
         "genders": clean_filter_values(schools_df.loc[_sec_mask, "gender"]) if "gender" in schools_df.columns and _sec_mask.any() else [],
         "admissions_policies": clean_filter_values(schools_df.loc[_sec_mask, "admissions_policy"]) if "admissions_policy" in schools_df.columns and _sec_mask.any() else [],
     }
@@ -1207,8 +1213,8 @@ async def get_filter_options(request: Request):
             "faiths": [],
         }
 
-    # Phases: return values from data, ordered sensibly
-    phases = clean_filter_values(df["phase"]) if "phase" in df.columns else []
+    # Phases: the values in the data, in the order a child meets them
+    phases = order_phases(clean_filter_values(df["phase"])) if "phase" in df.columns else []
 
     secondary_df = df[df["attainment_8_score"].notna()] if "attainment_8_score" in df.columns else df.iloc[0:0]
     genders = clean_filter_values(secondary_df["gender"]) if "gender" in secondary_df.columns else []
diff --git a/backend/schemas.py b/backend/schemas.py
index 5dbec05..005a815 100644
--- a/backend/schemas.py
+++ b/backend/schemas.py
@@ -544,6 +544,19 @@ PHASE_GROUPS: dict[str, set[str]] = {
     "all-through": {"all-through"},
 }
 
+# GIAS phases in the order a child meets them, for the phase filter's options.
+# All-through spans the whole path, so it follows the stages. Lowercased, as
+# PHASE_GROUPS is, so a change of case in the GIAS label keeps its place.
+PHASE_ORDER: list[str] = [
+    "nursery",
+    "primary",
+    "middle deemed primary",
+    "middle deemed secondary",
+    "secondary",
+    "16 plus",
+    "all-through",
+]
+
 # School listing columns
 SCHOOL_COLUMNS = [
     "urn",
diff --git a/backend/tests/test_phase_filter.py b/backend/tests/test_phase_filter.py
index f93bb26..b455f56 100644
--- a/backend/tests/test_phase_filter.py
+++ b/backend/tests/test_phase_filter.py
@@ -82,3 +82,25 @@ def test_grouped_phases_still_take_in_their_related_phases(client):
 
 def test_an_unknown_phase_returns_nothing_rather_than_everything(client):
     assert _urns(client, "kindergarten") == []
+
+
+def test_filters_lists_phases_in_the_order_a_child_meets_them(client):
+    # Alphabetical put "16 plus" and "All-through" first and Nursery fifth.
+    # All-through spans the whole path, so it comes after the stages.
+    assert client.get("/api/filters").json()["phases"] == [
+        "Nursery",
+        "Primary",
+        "Middle deemed primary",
+        "Middle deemed secondary",
+        "Secondary",
+        "16 plus",
+        "All-through",
+    ]
+
+
+def test_an_unknown_phase_follows_the_known_ones():
+    from backend.app import order_phases
+
+    assert order_phases(["Secondary", "Zeta", "Alpha", "Nursery"]) == [
+        "Nursery", "Secondary", "Alpha", "Zeta",
+    ]
diff --git a/e2e/tests/journeys.spec.ts b/e2e/tests/journeys.spec.ts
index ae585ee..13ebecf 100644
--- a/e2e/tests/journeys.spec.ts
+++ b/e2e/tests/journeys.spec.ts
@@ -286,6 +286,19 @@ test('the phase filter switches straight from secondary to primary', async ({ pa
   await expect(phase).toHaveValue('primary');
 });
 
+test('the phase filter lists phases in the order a child meets them', async ({ page }) => {
+  // They were alphabetical, so "16 plus" and "All-through" came before Nursery.
+  const childPath = ['Nursery', 'Primary', 'Middle deemed primary',
+    'Middle deemed secondary', 'Secondary', '16 plus', 'All-through'];
+  await page.goto('/?search=school');
+  const phase = page.getByRole('combobox', { name: 'Phase' });
+  await expect(phase).toBeVisible({ timeout: 15_000 });
+  const offered = (await phase.locator('option').allTextContents())
+    .filter((o) => childPath.includes(o));
+  expect(offered, 'no phase on offer').toContain('Primary');
+  expect(offered).toEqual(childPath.filter((p) => offered.includes(p)));
+});
+
 test('school type and gender switch straight to another value', async ({ page }) => {
   // Their options came from the result set, which the filter had already
   // narrowed, so with one value chosen it was the only one on offer.