diff --git a/ob-elixir.el b/ob-elixir.el
index 2e456b3..c6044d0 100644
--- a/ob-elixir.el
+++ b/ob-elixir.el
@@ -36,7 +36,9 @@
 
 (require 'ob)
 (require 'ob-eval)
+(require 'ob-comint)
 (require 'cl-lib)
+(require 'ansi-color)
 
 ;;; Customization
 
@@ -68,6 +70,26 @@ When nil, warnings are stripped from the output."
   :type 'boolean
   :group 'ob-elixir)
 
+;;; Session Configuration
+
+(defcustom ob-elixir-iex-command "iex"
+  "Command to start IEx session."
+  :type 'string
+  :group 'ob-elixir
+  :safe #'stringp)
+
+(defconst ob-elixir--prompt-regexp
+  "^\\(?:iex\\|\\.\\.\\)([0-9]+)> "
+  "Regexp matching IEx prompt.
+Matches both regular prompt `iex(N)> ' and continuation `...(N)> '.")
+
+(defconst ob-elixir--eoe-marker
+  "__ob_elixir_eoe_marker__"
+  "End-of-evaluation marker for session output.")
+
+(defvar ob-elixir--sessions (make-hash-table :test 'equal)
+  "Hash table mapping session names to buffer names.")
+
 ;;; Header Arguments
 
 (defvar org-babel-default-header-args:elixir
@@ -363,6 +385,204 @@ Each statement has the form: var_name = value"
                (ob-elixir--elisp-to-elixir value))))
    (org-babel--get-vars params)))
 
+;;; Session Management
+
+(defun org-babel-elixir-initiate-session (&optional session params)
+  "Create or return an Elixir session buffer.
+
+SESSION is the session name (string or nil).
+PARAMS are the header arguments.
+
+Returns the session buffer, or nil if SESSION is \"none\"."
+  (unless (or (not session) (string= session "none"))
+    (let* ((session-name (if (stringp session) session "default"))
+           (buffer (ob-elixir--get-or-create-session session-name params)))
+      (when buffer
+        (puthash session-name (buffer-name buffer) ob-elixir--sessions))
+      buffer)))
+
+(defun ob-elixir--get-or-create-session (name params)
+  "Get or create an IEx session named NAME with PARAMS."
+  (let* ((buffer-name (format "*ob-elixir:%s*" name))
+         (existing (get-buffer buffer-name)))
+    (if (and existing (org-babel-comint-buffer-livep existing))
+        existing
+      (ob-elixir--start-session buffer-name name params))))
+
+(defun ob-elixir--start-session (buffer-name session-name _params)
+  "Start a new IEx session in BUFFER-NAME.
+SESSION-NAME is used for the process name.
+_PARAMS is reserved for future use."
+  (let* ((buffer (get-buffer-create buffer-name))
+         (process-environment (cons "TERM=dumb" process-environment)))
+    (with-current-buffer buffer
+      ;; Start the IEx process
+      (make-comint-in-buffer
+       (format "ob-elixir-%s" session-name)
+       buffer
+       ob-elixir-iex-command
+       nil)
+
+      ;; Wait for initial prompt
+      (ob-elixir--wait-for-prompt buffer 10)
+
+      ;; Configure IEx for programmatic use
+      (ob-elixir--configure-session buffer)
+
+      buffer)))
+
+(defun ob-elixir--configure-session (buffer)
+  "Configure IEx session in BUFFER for programmatic use."
+  (let ((config-commands
+         '("IEx.configure(colors: [enabled: false])"
+           "IEx.configure(inspect: [limit: :infinity, printable_limit: :infinity])")))
+    (dolist (cmd config-commands)
+      (ob-elixir--send-command buffer cmd)
+      (ob-elixir--wait-for-prompt buffer 5))))
+
+;;; Session Prompt Detection
+
+(defun ob-elixir--wait-for-prompt (buffer timeout)
+  "Wait for IEx prompt in BUFFER with TIMEOUT seconds."
+  (with-current-buffer buffer
+    (let ((end-time (+ (float-time) timeout)))
+      (while (and (< (float-time) end-time)
+                  (not (ob-elixir--at-prompt-p)))
+        (accept-process-output (get-buffer-process buffer) 0.1)
+        (goto-char (point-max)))
+      (ob-elixir--at-prompt-p))))
+
+(defun ob-elixir--at-prompt-p ()
+  "Return t if the last line in buffer looks like an IEx prompt."
+  (save-excursion
+    (goto-char (point-max))
+    (forward-line 0)
+    (looking-at ob-elixir--prompt-regexp)))
+
+;;; Session Command Sending
+
+(defun ob-elixir--send-command (buffer command)
+  "Send COMMAND to IEx process in BUFFER."
+  (with-current-buffer buffer
+    (goto-char (point-max))
+    (insert command)
+    (comint-send-input nil t)))
+
+(defconst ob-elixir--session-value-wrapper
+  "_ob_result_ = (
+%s
+)
+IO.puts(\"__ob_value_start__\")
+IO.puts(inspect(_ob_result_, limit: :infinity, printable_limit: :infinity))
+IO.puts(\"__ob_value_end__\")
+:ok
+"
+  "Wrapper for capturing value in session mode.")
+
+(defun ob-elixir--session-wrap-for-value (body)
+  "Wrap BODY to capture its value in session mode."
+  (format ob-elixir--session-value-wrapper body))
+
+(defun ob-elixir--evaluate-in-session (session body result-type)
+  "Evaluate BODY in SESSION, return result.
+
+RESULT-TYPE is `value' or `output'."
+  (let* ((buffer (org-babel-elixir-initiate-session session nil))
+         (code (if (eq result-type 'value)
+                   (ob-elixir--session-wrap-for-value body)
+                 body))
+         (eoe-indicator ob-elixir--eoe-marker)
+         (full-body (concat code "\nIO.puts(\"" eoe-indicator "\")"))
+         output)
+    (unless buffer
+      (error "Failed to create Elixir session: %s" session))
+
+    (setq output
+          (org-babel-comint-with-output
+              (buffer eoe-indicator t full-body)
+            (ob-elixir--send-command buffer full-body)))
+
+    (ob-elixir--clean-session-output output result-type)))
+
+;;; Session Output Extraction
+
+(defun ob-elixir--extract-session-output (buffer start-marker)
+  "Extract output from BUFFER since START-MARKER."
+  (with-current-buffer buffer
+    (let ((end-pos (point-max)))
+      (buffer-substring-no-properties start-marker end-pos))))
+
+(defun ob-elixir--clean-session-output (output result-type)
+  "Clean OUTPUT from IEx session.
+RESULT-TYPE is `value' or `output'."
+  (let ((result (if (listp output)
+                    (mapconcat #'identity output "\n")
+                  output)))
+    ;; Remove ANSI escape codes
+    (setq result (ansi-color-filter-apply result))
+
+    ;; Remove prompts (including continuation prompts)
+    (setq result (replace-regexp-in-string
+                  "^\\(?:iex\\|\\.\\.\\)([0-9]+)> *" "" result))
+
+    ;; Remove EOE marker output
+    (setq result (replace-regexp-in-string
+                  (regexp-quote ob-elixir--eoe-marker) "" result))
+
+    ;; For value results, extract the value between markers
+    (when (eq result-type 'value)
+      (if (string-match "__ob_value_start__\n\\(\\(?:.\\|\n\\)*?\\)\n__ob_value_end__" result)
+          (setq result (match-string 1 result))
+        ;; Fallback: remove wrapper artifacts
+        (setq result (replace-regexp-in-string
+                      "^_ob_result_ = (\n?" "" result))
+        (setq result (replace-regexp-in-string
+                      "\n?)$" "" result))
+        (setq result (replace-regexp-in-string
+                      "^IO\\.puts.*\n?" "" result))
+        (setq result (replace-regexp-in-string
+                      ":ok$" "" result))))
+
+    (string-trim result)))
+
+;;; Session Prep
+
+(defun org-babel-prep-session:elixir (session params)
+  "Prepare SESSION according to PARAMS.
+
+Sends variable assignments to the session."
+  (let ((buffer (org-babel-elixir-initiate-session session params))
+        (var-lines (org-babel-variable-assignments:elixir params)))
+    (when (and buffer var-lines)
+      (dolist (var-line var-lines)
+        (ob-elixir--send-command buffer var-line)
+        (ob-elixir--wait-for-prompt buffer 5)))
+    buffer))
+
+;;; Session Cleanup
+
+(defun ob-elixir-kill-session (session)
+  "Kill the Elixir session named SESSION."
+  (interactive
+   (list (completing-read "Kill session: "
+                          (hash-table-keys ob-elixir--sessions))))
+  (let ((buffer-name (gethash session ob-elixir--sessions)))
+    (when buffer-name
+      (let ((buffer (get-buffer buffer-name)))
+        (when buffer
+          (let ((process (get-buffer-process buffer)))
+            (when process
+              (delete-process process)))
+          (kill-buffer buffer)))
+      (remhash session ob-elixir--sessions))))
+
+(defun ob-elixir-kill-all-sessions ()
+  "Kill all Elixir sessions."
+  (interactive)
+  (maphash (lambda (name _buffer)
+             (ob-elixir-kill-session name))
+           ob-elixir--sessions))
+
 ;;; Execution
 
 (defconst ob-elixir--value-wrapper
@@ -411,13 +631,18 @@ BODY is the Elixir code to execute.
 PARAMS is an alist of header arguments.
 
 This function is called by `org-babel-execute-src-block'."
-  (let* ((result-type (cdr (assq :result-type params)))
+  (let* ((session (cdr (assq :session params)))
+         (result-type (cdr (assq :result-type params)))
          (result-params (cdr (assq :result-params params)))
          ;; Expand body with variable assignments
          (full-body (org-babel-expand-body:generic
                      body params
                      (org-babel-variable-assignments:elixir params)))
-         (result (ob-elixir--execute full-body result-type)))
+         (result (if (and session (not (string= session "none")))
+                     ;; Session mode
+                     (ob-elixir--evaluate-in-session session full-body result-type)
+                   ;; External process mode
+                   (ob-elixir--execute full-body result-type))))
     (org-babel-reassemble-table
      (org-babel-result-cond result-params
        ;; For output/scalar/verbatim - return as-is
diff --git a/test/test-ob-elixir-sessions.el b/test/test-ob-elixir-sessions.el
new file mode 100644
index 0000000..c8d3bc0
--- /dev/null
+++ b/test/test-ob-elixir-sessions.el
@@ -0,0 +1,114 @@
+;;; test-ob-elixir-sessions.el --- Session tests for ob-elixir -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2024
+
+;;; Commentary:
+
+;; Tests for IEx session support in ob-elixir.
+
+;;; Code:
+
+(require 'ert)
+(require 'ob-elixir)
+
+(ert-deftest ob-elixir-test-session-creation ()
+  "Test session creation."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (unwind-protect
+      (let ((buffer (org-babel-elixir-initiate-session "test-create" nil)))
+        (should buffer)
+        (should (org-babel-comint-buffer-livep buffer)))
+    (ob-elixir-kill-session "test-create")))
+
+(ert-deftest ob-elixir-test-session-persistence ()
+  "Test that sessions persist state."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (unwind-protect
+      (progn
+        ;; First evaluation - define variable
+        (ob-elixir--evaluate-in-session "test-persist" "x = 42" 'value)
+        ;; Second evaluation - use variable
+        (let ((result (ob-elixir--evaluate-in-session
+                       "test-persist" "x * 2" 'value)))
+          (should (equal "84" result))))
+    (ob-elixir-kill-session "test-persist")))
+
+(ert-deftest ob-elixir-test-session-none ()
+  "Test that :session none uses external process."
+  (skip-unless (executable-find ob-elixir-command))
+  (should (null (org-babel-elixir-initiate-session "none" nil))))
+
+(ert-deftest ob-elixir-test-session-module-def ()
+  "Test defining module in session."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (unwind-protect
+      (progn
+        (ob-elixir--evaluate-in-session
+         "test-module"
+         "defmodule TestMod do\n  def double(x), do: x * 2\nend"
+         'value)
+        (let ((result (ob-elixir--evaluate-in-session
+                       "test-module" "TestMod.double(21)" 'value)))
+          (should (equal "42" result))))
+    (ob-elixir-kill-session "test-module")))
+
+(ert-deftest ob-elixir-test-session-reuse ()
+  "Test that same session name returns same buffer."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (unwind-protect
+      (let ((buffer1 (org-babel-elixir-initiate-session "test-reuse" nil))
+            (buffer2 (org-babel-elixir-initiate-session "test-reuse" nil)))
+        (should (eq buffer1 buffer2)))
+    (ob-elixir-kill-session "test-reuse")))
+
+(ert-deftest ob-elixir-test-multiple-sessions ()
+  "Test that multiple named sessions work independently."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (unwind-protect
+      (progn
+        ;; Set x in session-a
+        (ob-elixir--evaluate-in-session "session-a" "x = 1" 'value)
+        ;; Set x in session-b to different value
+        (ob-elixir--evaluate-in-session "session-b" "x = 100" 'value)
+        ;; Verify each session has its own value
+        (let ((result-a (ob-elixir--evaluate-in-session "session-a" "x" 'value))
+              (result-b (ob-elixir--evaluate-in-session "session-b" "x" 'value)))
+          (should (equal "1" result-a))
+          (should (equal "100" result-b))))
+    (ob-elixir-kill-session "session-a")
+    (ob-elixir-kill-session "session-b")))
+
+(ert-deftest ob-elixir-test-session-output-mode ()
+  "Test session output mode (capturing stdout)."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (unwind-protect
+      (let ((result (ob-elixir--evaluate-in-session
+                     "test-output"
+                     "IO.puts(\"Hello from session\")"
+                     'output)))
+        (should (string-match-p "Hello from session" result)))
+    (ob-elixir-kill-session "test-output")))
+
+(ert-deftest ob-elixir-test-kill-session ()
+  "Test killing a session."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (let ((buffer (org-babel-elixir-initiate-session "test-kill" nil)))
+    (should buffer)
+    (ob-elixir-kill-session "test-kill")
+    (should-not (buffer-live-p buffer))
+    (should-not (gethash "test-kill" ob-elixir--sessions))))
+
+(ert-deftest ob-elixir-test-kill-all-sessions ()
+  "Test killing all sessions."
+  (skip-unless (executable-find ob-elixir-iex-command))
+  (let ((buffer1 (org-babel-elixir-initiate-session "test-all-1" nil))
+        (buffer2 (org-babel-elixir-initiate-session "test-all-2" nil)))
+    (should buffer1)
+    (should buffer2)
+    (ob-elixir-kill-all-sessions)
+    (should-not (buffer-live-p buffer1))
+    (should-not (buffer-live-p buffer2))
+    (should (= 0 (hash-table-count ob-elixir--sessions)))))
+
+(provide 'test-ob-elixir-sessions)
+;;; test-ob-elixir-sessions.el ends here