diff --git a/lib/erlang/runtime.sx b/lib/erlang/runtime.sx
index c8d19a27..03aaad5d 100644
--- a/lib/erlang/runtime.sx
+++ b/lib/erlang/runtime.sx
@@ -150,6 +150,7 @@
         :current nil
         :processes {}
         :registered {}
+        :ets {}
         :runnable (er-q-new)})))
 
 (define er-sched (fn () (nth er-scheduler 0)))
@@ -1025,3 +1026,179 @@
 (define
   er-load-supervisor!
   (fn () (erlang-load-module er-supervisor-source)))
+
+;; ── ETS-lite ────────────────────────────────────────────────────
+;; Each table is a mutable list of tuples; key is the tuple's first
+;; element (keypos=1, the default). Tables live on the scheduler
+;; under `:ets` keyed by the registering atom name. Set semantics:
+;; `insert/2` replaces an existing entry with the same key.
+(define er-ets-tables (fn () (get (er-sched) :ets)))
+
+(define
+  er-bif-ets-new
+  (fn
+    (vs)
+    (cond
+      (not (= (len vs) 2)) (error "Erlang: ets:new/2: arity")
+      :else (let
+        ((name (nth vs 0)))
+        (cond
+          (not (er-atom? name))
+          (raise (er-mk-error-marker (er-mk-atom "badarg")))
+          (dict-has? (er-ets-tables) (get name :name))
+          (raise
+            (er-mk-error-marker
+              (er-mk-tuple (list (er-mk-atom "badarg") name))))
+          :else (do
+            (dict-set! (er-ets-tables) (get name :name) (list))
+            name))))))
+
+(define
+  er-ets-resolve
+  (fn
+    (id)
+    (cond
+      (not (er-atom? id))
+      (raise (er-mk-error-marker (er-mk-atom "badarg")))
+      (not (dict-has? (er-ets-tables) (get id :name)))
+      (raise (er-mk-error-marker (er-mk-atom "badarg")))
+      :else (get (er-ets-tables) (get id :name)))))
+
+(define
+  er-bif-ets-insert
+  (fn
+    (vs)
+    (cond
+      (not (= (len vs) 2)) (error "Erlang: ets:insert/2: arity")
+      :else (let
+        ((tab (er-ets-resolve (nth vs 0)))
+          (entry (nth vs 1)))
+        (cond
+          (not (er-tuple? entry))
+          (raise (er-mk-error-marker (er-mk-atom "badarg")))
+          (= (len (get entry :elements)) 0)
+          (raise (er-mk-error-marker (er-mk-atom "badarg")))
+          :else (do
+            (er-ets-replace-or-append! tab entry)
+            (er-mk-atom "true")))))))
+
+(define
+  er-ets-replace-or-append!
+  (fn
+    (tab entry)
+    (let
+      ((key (nth (get entry :elements) 0))
+        (replaced (list false)))
+      (for-each
+        (fn
+          (i)
+          (when
+            (er-equal? (nth (get (nth tab i) :elements) 0) key)
+            (set-nth! tab i entry)
+            (set-nth! replaced 0 true)))
+        (range 0 (len tab)))
+      (when (not (nth replaced 0)) (append! tab entry)))))
+
+(define
+  er-bif-ets-lookup
+  (fn
+    (vs)
+    (cond
+      (not (= (len vs) 2)) (error "Erlang: ets:lookup/2: arity")
+      :else (let
+        ((tab (er-ets-resolve (nth vs 0)))
+          (key (nth vs 1))
+          (out (er-mk-nil)))
+        (for-each
+          (fn
+            (i)
+            (let
+              ((j (- (- (len tab) 1) i))
+                (entry (nth tab (- (- (len tab) 1) i))))
+              (when
+                (er-equal? (nth (get entry :elements) 0) key)
+                (set! out (er-mk-cons entry out)))))
+          (range 0 (len tab)))
+        out))))
+
+(define
+  er-bif-ets-delete
+  (fn
+    (vs)
+    (cond
+      (= (len vs) 1) (er-ets-delete-table! (nth vs 0))
+      (= (len vs) 2) (er-ets-delete-key! (nth vs 0) (nth vs 1))
+      :else (error "Erlang: ets:delete: arity"))))
+
+(define
+  er-ets-delete-table!
+  (fn
+    (id)
+    (cond
+      (not (er-atom? id))
+      (raise (er-mk-error-marker (er-mk-atom "badarg")))
+      (not (dict-has? (er-ets-tables) (get id :name)))
+      (raise (er-mk-error-marker (er-mk-atom "badarg")))
+      :else (do
+        (dict-delete! (er-ets-tables) (get id :name))
+        (er-mk-atom "true")))))
+
+(define
+  er-ets-delete-key!
+  (fn
+    (id key)
+    (let
+      ((tab (er-ets-resolve id)) (out (list)))
+      (for-each
+        (fn
+          (i)
+          (let
+            ((entry (nth tab i)))
+            (when
+              (not (er-equal? (nth (get entry :elements) 0) key))
+              (append! out entry))))
+        (range 0 (len tab)))
+      (dict-set! (er-ets-tables) (get id :name) out)
+      (er-mk-atom "true"))))
+
+(define
+  er-bif-ets-tab2list
+  (fn
+    (vs)
+    (let
+      ((tab (er-ets-resolve (er-bif-arg1 vs "ets:tab2list"))) (out (er-mk-nil)))
+      (for-each
+        (fn
+          (i)
+          (let
+            ((j (- (- (len tab) 1) i)))
+            (set! out (er-mk-cons (nth tab j) out))))
+        (range 0 (len tab)))
+      out)))
+
+(define
+  er-bif-ets-info
+  (fn
+    (vs)
+    (cond
+      (= (len vs) 2)
+      (let
+        ((tab (er-ets-resolve (nth vs 0))) (key (nth vs 1)))
+        (cond
+          (and (er-atom? key) (= (get key :name) "size")) (len tab)
+          :else (er-mk-atom "undefined")))
+      :else (error "Erlang: ets:info: arity"))))
+
+(define
+  er-apply-ets-bif
+  (fn
+    (name vs)
+    (cond
+      (= name "new") (er-bif-ets-new vs)
+      (= name "insert") (er-bif-ets-insert vs)
+      (= name "lookup") (er-bif-ets-lookup vs)
+      (= name "delete") (er-bif-ets-delete vs)
+      (= name "tab2list") (er-bif-ets-tab2list vs)
+      (= name "info") (er-bif-ets-info vs)
+      :else (error
+        (str "Erlang: undefined 'ets:" name "/" (len vs) "'")))))
diff --git a/lib/erlang/scoreboard.json b/lib/erlang/scoreboard.json
index cf98c8d9..639149b7 100644
--- a/lib/erlang/scoreboard.json
+++ b/lib/erlang/scoreboard.json
@@ -1,11 +1,11 @@
 {
   "language": "erlang",
-  "total_pass": 477,
-  "total": 477,
+  "total_pass": 490,
+  "total": 490,
   "suites": [
     {"name":"tokenize","pass":62,"total":62,"status":"ok"},
     {"name":"parse","pass":52,"total":52,"status":"ok"},
-    {"name":"eval","pass":293,"total":293,"status":"ok"},
+    {"name":"eval","pass":306,"total":306,"status":"ok"},
     {"name":"runtime","pass":39,"total":39,"status":"ok"},
     {"name":"ring","pass":4,"total":4,"status":"ok"},
     {"name":"ping-pong","pass":4,"total":4,"status":"ok"},
diff --git a/lib/erlang/scoreboard.md b/lib/erlang/scoreboard.md
index 86429df7..e17aad1d 100644
--- a/lib/erlang/scoreboard.md
+++ b/lib/erlang/scoreboard.md
@@ -1,12 +1,12 @@
 # Erlang-on-SX Scoreboard
 
-**Total: 477 / 477 tests passing**
+**Total: 490 / 490 tests passing**
 
 |  | Suite | Pass | Total |
 |---|---|---|---|
 | ✅ | tokenize | 62 | 62 |
 | ✅ | parse | 52 | 52 |
-| ✅ | eval | 293 | 293 |
+| ✅ | eval | 306 | 306 |
 | ✅ | runtime | 39 | 39 |
 | ✅ | ring | 4 | 4 |
 | ✅ | ping-pong | 4 | 4 |
diff --git a/lib/erlang/tests/eval.sx b/lib/erlang/tests/eval.sx
index e2ad5eb9..2bb54aae 100644
--- a/lib/erlang/tests/eval.sx
+++ b/lib/erlang/tests/eval.sx
@@ -994,6 +994,55 @@
 (er-eval-test "build with size var"
   (ev "X = 7, byte_size(<<X:16>>)") 2)
 
+;; ── ETS-lite ──────────────────────────────────────────────────
+(er-eval-test "ets:new returns name"
+  (nm (ev "ets:new(t1, [set])")) "t1")
+(er-eval-test "ets:insert returns true"
+  (nm (ev "T = ets:new(t2, [set]), ets:insert(T, {foo, 1})")) "true")
+(er-eval-test "ets:lookup hit"
+  (ev "T = ets:new(t3, [set]), ets:insert(T, {foo, 42}), [{foo, V}] = ets:lookup(T, foo), V")
+  42)
+(er-eval-test "ets:lookup miss returns []"
+  (get (ev "T = ets:new(t4, [set]), ets:lookup(T, no_such)") :tag) "nil")
+(er-eval-test "ets:insert replaces (set semantics)"
+  (ev "T = ets:new(t5, [set]), ets:insert(T, {x, 1}), ets:insert(T, {x, 2}), ets:insert(T, {x, 3}), [{x, V}] = ets:lookup(T, x), V")
+  3)
+(er-eval-test "ets:info size grows"
+  (ev "T = ets:new(t6, [set]), ets:insert(T, {a, 1}), ets:insert(T, {b, 2}), ets:insert(T, {c, 3}), ets:info(T, size)")
+  3)
+(er-eval-test "ets:info size after delete"
+  (ev "T = ets:new(t7, [set]), ets:insert(T, {a, 1}), ets:insert(T, {b, 2}), ets:delete(T, a), ets:info(T, size)")
+  1)
+(er-eval-test "ets:tab2list length"
+  (ev "T = ets:new(t8, [set]), ets:insert(T, {a, 1}), ets:insert(T, {b, 2}), ets:insert(T, {c, 3}), length(ets:tab2list(T))")
+  3)
+(er-eval-test "ets:delete table returns true"
+  (nm (ev "T = ets:new(t9, [set]), ets:delete(T)")) "true")
+(er-eval-test "ets:lookup after table delete"
+  (do
+    (ev "P = spawn(fun () -> T = ets:new(t10, [set]), ets:delete(T), ets:lookup(T, x) end), receive after 0 -> ok end")
+    (let ((reason (er-proc-field (er-mk-pid 1) :exit-reason)))
+      (cond
+        (er-atom? reason) (get reason :name)
+        :else (nm reason))))
+  "badarg")
+
+;; Sum a column via lookup chain.
+(er-eval-test "ets aggregate"
+  (ev "T = ets:new(t11, [set]), ets:insert(T, {a, 10}), ets:insert(T, {b, 20}), ets:insert(T, {c, 30}), [{a, A}] = ets:lookup(T, a), [{b, B}] = ets:lookup(T, b), [{c, C}] = ets:lookup(T, c), A + B + C")
+  60)
+
+;; Tuple key (non-atom).
+(er-eval-test "ets tuple key"
+  (nm
+    (ev "T = ets:new(t12, [set]), ets:insert(T, {{x, 1}, hello}), [{{x, 1}, V}] = ets:lookup(T, {x, 1}), V"))
+  "hello")
+
+;; Tables are independent.
+(er-eval-test "ets two tables independent"
+  (ev "T1 = ets:new(t13, [set]), T2 = ets:new(t14, [set]), ets:insert(T1, {x, 1}), ets:insert(T2, {x, 99}), [{x, A}] = ets:lookup(T1, x), [{x, B}] = ets:lookup(T2, x), A + B")
+  100)
+
 (define
   er-eval-test-summary
   (str "eval " er-eval-test-pass "/" er-eval-test-count))
diff --git a/lib/erlang/transpile.sx b/lib/erlang/transpile.sx
index d3d7bd18..72893644 100644
--- a/lib/erlang/transpile.sx
+++ b/lib/erlang/transpile.sx
@@ -718,6 +718,7 @@
       (= mod "lists") (er-apply-lists-bif name vs)
       (= mod "io") (er-apply-io-bif name vs)
       (= mod "erlang") (er-apply-bif name vs)
+      (= mod "ets") (er-apply-ets-bif name vs)
       :else (error
         (str "Erlang: undefined module '" mod "'")))))
 
diff --git a/plans/erlang-on-sx.md b/plans/erlang-on-sx.md
index b27b0a15..80e405ae 100644
--- a/plans/erlang-on-sx.md
+++ b/plans/erlang-on-sx.md
@@ -92,13 +92,14 @@ Core mapping:
 ### Phase 6 — the rest
 - [x] List comprehensions `[X*2 || X <- L]` — **12 new eval tests**; generators, filters, multiple generators (cartesian), pattern-matching gens (`{ok, V} <- ...`)
 - [x] Binary pattern matching `<<A:8, B:16>>` — **21 new eval tests**; literal construction, byte/multi-byte segments, `Rest/binary` tail capture, `is_binary/1`, `byte_size/1`
-- [ ] ETS-lite (in-memory tables via SX dicts)
+- [x] ETS-lite (in-memory tables via SX dicts) — **13 new eval tests**; `ets:new/2`, `insert/2`, `lookup/2`, `delete/1-2`, `tab2list/1`, `info/2` (size); set semantics with full Erlang-term keys
 - [ ] More BIFs — target 200+ test corpus green
 
 ## Progress log
 
 _Newest first._
 
+- **2026-04-25 ETS-lite green** — Scheduler state gains `:ets` (table-name → mutable list of tuples). New `er-apply-ets-bif` dispatches `ets:new/2` (registers table by atom name; rejects duplicate name with `{badarg, Name}`), `insert/2` (set semantics — replaces existing entry with the same first-element key, else appends), `lookup/2` (returns Erlang list — `[Tuple]` if found else `[]`), `delete/1` (drop table), `delete/2` (drop key; rebuilds entry list), `tab2list/1` (full list view), `info/2` with `size` only. Keys are full Erlang terms compared via `er-equal?`. 13 new eval tests: new return value, insert true, lookup hit + miss, set replace, info size after insert/delete, tab2list length, table delete, lookup-after-delete raises badarg, multi-key aggregate sum, tuple-key insert + lookup, two independent tables. Total suite 490/490.
 - **2026-04-25 binary pattern matching green** — Parser additions: `<<...>>` literal/pattern in `er-parse-primary`, segment grammar `Value [: Size] [/ Spec]` (Spec defaults to `integer`, supports `binary` for tail). Critical fix: segment value uses `er-parse-primary` (not `er-parse-expr-prec`) so the trailing `:Size` doesn't get eaten by the postfix `Mod:Fun` remote-call handler. Runtime value: `{:tag "binary" :bytes (list of int 0-255)}`. Construction: integer segments emit big-endian bytes (size in bits, must be multiple of 8); binary-spec segments concatenate. Pattern matching consumes bytes from a cursor at the front, decoding integer segments big-endian, capturing `Rest/binary` tail at the end. Whole-binary length must consume exactly. New BIFs: `is_binary/1`, `byte_size/1`. Binaries participate in `er-equal?` (byte-wise) and format as `<<b1,b2,...>>`. 21 new eval tests: tag/predicate, byte_size for 8/16/32-bit segments, single + multi segment match, three 8-bit, tail rest size + content, badmatch on size mismatch, `=:=` equality, var-driven construction. Total suite 477/477.
 - **2026-04-25 list comprehensions green** — Parser additions in `lib/erlang/parser-expr.sx`: after the first expr in `[`, peek for `||` punct and dispatch to `er-parse-list-comp`. Qualifiers separated by `,`, each one is `Pattern <- Source` (generator) or any expression (filter — disambiguated by absence of `<-`). AST: `{:type "lc" :head E :qualifiers [...]}` with each qualifier `{:kind "gen"/"filter" ...}`. Evaluator (`er-eval-lc` in transpile.sx): right-fold builds the result by walking qualifiers; generators iterate the source list with env snapshot/restore per element so pattern-bound vars don't leak between iterations; filters skip when falsy. Pattern-matching generators are silently skipped on no-match (e.g. `[V || {ok, V} <- ...]`). 12 new eval tests: map double, fold-sum-of-comprehension, length, filter sum, "all filtered", empty source, cartesian, pattern-match gen, nested generators with filter, squares, tuple capture. Total suite 456/456.
 - **2026-04-25 register/whereis green — Phase 5 complete** — Scheduler state gains `:registered` (atom-name → pid). New BIFs: `register/2` (badarg on non-atom name, non-pid target, dead pid, or duplicate name), `unregister/1`, `whereis/1` (returns pid or atom `undefined`), `registered/0` (Erlang list of name atoms). `er-eval-send` for `Name ! Msg`: now resolves the target — pid passes through, atom looks up registered name and raises `{badarg, Name}` if missing, anything else raises badarg. Process death (in `er-sched-step!`) calls `er-unregister-pid!` to drop any registered name before `er-propagate-exit!` so monitor `{'DOWN'}` messages see the cleared registry. 12 new eval tests: register returns true, whereis self/undefined, send via registered atom, send to spawned-then-registered child, unregister + whereis, registered/0 list length, dup register raises, missing unregister raises, dead-process auto-unregisters via send-die-then-whereis, send to unknown name raises. Total suite 444/444. **Phase 5 complete — Phase 6 (list comprehensions, binary patterns, ETS) is the last phase.**