diff --git a/pyproject.toml b/pyproject.toml
index 9d7bb3d..3e05965 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "x-cli"
-version = "0.1.0"
+version = "0.2.0"
 description = "CLI for X/Twitter API v2"
 requires-python = ">=3.11"
 dependencies = [
diff --git a/src/x_cli/api.py b/src/x_cli/api.py
index 62282d9..ba3afc2 100644
--- a/src/x_cli/api.py
+++ b/src/x_cli/api.py
@@ -11,6 +11,14 @@
 API_BASE = "https://api.x.com/2"
 
 
+class RateLimitError(RuntimeError):
+    """Raised when the API returns HTTP 429."""
+
+    def __init__(self, reset_at: str) -> None:
+        self.reset_at = reset_at
+        super().__init__(f"Rate limited. Resets at {reset_at}.")
+
+
 class XApiClient:
     def __init__(self, creds: Credentials) -> None:
         self.creds = creds
@@ -37,7 +45,7 @@ def _oauth_request(self, method: str, url: str, json_body: dict | None = None) -
     def _handle(self, resp: httpx.Response) -> dict[str, Any]:
         if resp.status_code == 429:
             reset = resp.headers.get("x-rate-limit-reset", "unknown")
-            raise RuntimeError(f"Rate limited. Resets at {reset}.")
+            raise RateLimitError(reset)
         data = resp.json()
         if not resp.is_success:
             errors = data.get("errors", [])
@@ -108,7 +116,9 @@ def get_user(self, username: str) -> dict[str, Any]:
         fields = "user.fields=created_at,description,public_metrics,verified,profile_image_url,url,location,pinned_tweet_id"
         return self._bearer_get(f"{API_BASE}/users/by/username/{username}?{fields}")
 
-    def get_timeline(self, user_id: str, max_results: int = 10) -> dict[str, Any]:
+    def get_timeline(
+        self, user_id: str, max_results: int = 10, since_id: str | None = None
+    ) -> dict[str, Any]:
         max_results = max(5, min(max_results, 100))
         params = {
             "max_results": str(max_results),
@@ -117,6 +127,8 @@ def get_timeline(self, user_id: str, max_results: int = 10) -> dict[str, Any]:
             "user.fields": "name,username,verified",
             "media.fields": "url,preview_image_url,type",
         }
+        if since_id:
+            params["since_id"] = since_id
         resp = self._http.get(
             f"{API_BASE}/users/{user_id}/tweets",
             params=params,
diff --git a/src/x_cli/cli.py b/src/x_cli/cli.py
index 7816e3e..3a2929a 100644
--- a/src/x_cli/cli.py
+++ b/src/x_cli/cli.py
@@ -9,6 +9,7 @@
 from .auth import load_credentials
 from .formatters import format_output
 from .utils import parse_tweet_id, strip_at
+from .watch import WatchTarget, watch_loop
 
 
 class State:
@@ -254,6 +255,50 @@ def retweet(state, id_or_url):
     state.output(data, "Retweeted")
 
 
+# ============================================================
+# watch
+# ============================================================
+
+@cli.command("watch")
+@click.argument("usernames", nargs=-1, required=True)
+@click.option("--interval", "-i", default=60, type=int, help="Poll interval in seconds (default: 60)")
+@click.option("--filter", "-f", "filters", multiple=True, help="Only show tweets containing keyword (repeatable)")
+@click.option("--notify", "-n", is_flag=True, default=False, help="Desktop notifications for new tweets")
+@click.option("--max", "max_tweets", default=None, type=int, help="Stop after N tweets")
+@pass_state
+def watch(state, usernames, interval, filters, notify, max_tweets):
+    """Watch accounts for new tweets in real-time.
+
+    \b
+    Examples:
+      x-cli watch CheddarFlow
+      x-cli watch CheddarFlow unusual_whales --interval 30
+      x-cli watch CheddarFlow -f "$NVDA" -f "$TSLA"
+      x-cli watch CheddarFlow --notify --max 50
+    """
+    # Resolve usernames to user IDs
+    targets = []
+    for username in usernames:
+        uname = strip_at(username)
+        try:
+            user_data = state.client.get_user(uname)
+            uid = user_data["data"]["id"]
+            targets.append(WatchTarget(username=uname, user_id=uid))
+        except RuntimeError as e:
+            raise click.ClickException(f"Could not find user @{uname}: {e}")
+
+    watch_loop(
+        client=state.client,
+        targets=targets,
+        interval=interval,
+        filters=list(filters),
+        notify=notify,
+        max_tweets=max_tweets,
+        mode=state.mode,
+        verbose=state.verbose,
+    )
+
+
 def main():
     cli()
 
diff --git a/src/x_cli/watch.py b/src/x_cli/watch.py
new file mode 100644
index 0000000..cceb67a
--- /dev/null
+++ b/src/x_cli/watch.py
@@ -0,0 +1,168 @@
+"""Watch mode: poll accounts for new tweets in real-time."""
+
+from __future__ import annotations
+
+import platform
+import subprocess
+import sys
+import time
+from dataclasses import dataclass, field
+from typing import Any
+
+from rich.console import Console
+
+from .api import RateLimitError, XApiClient
+from .formatters import format_output
+
+_stderr = Console(stderr=True)
+
+
+@dataclass
+class WatchTarget:
+    """A user being watched."""
+
+    username: str
+    user_id: str
+    last_seen_id: str | None = None
+
+
+@dataclass
+class WatchStats:
+    """Accumulated stats for the session."""
+
+    tweets_seen: int = 0
+    polls: int = 0
+    per_user: dict[str, int] = field(default_factory=dict)
+
+
+def _matches_filters(text: str, filters: list[str]) -> bool:
+    """Return True if tweet text matches any of the filter keywords (case-insensitive)."""
+    if not filters:
+        return True
+    text_lower = text.lower()
+    return any(f.lower() in text_lower for f in filters)
+
+
+def _notify(username: str, text: str) -> None:
+    """Send a desktop notification (macOS only, silent fail elsewhere)."""
+    if platform.system() != "Darwin":
+        print("\a", end="", flush=True)  # terminal bell fallback
+        return
+    preview = text[:100].replace('"', '\\"').replace("\n", " ")
+    script = f'display notification "{preview}" with title "x-cli: @{username}"'
+    try:
+        subprocess.run(["osascript", "-e", script], capture_output=True, timeout=5)
+    except Exception:
+        pass
+
+
+def _seed_last_seen(client: XApiClient, target: WatchTarget) -> None:
+    """Fetch the most recent tweet ID so we only show new ones."""
+    try:
+        data = client.get_timeline(target.user_id, max_results=5)
+        tweets = data.get("data", [])
+        if tweets:
+            target.last_seen_id = tweets[0]["id"]
+    except RuntimeError:
+        pass
+
+
+def _print_summary(stats: WatchStats, targets: list[WatchTarget]) -> None:
+    _stderr.print()
+    _stderr.print("[bold]Watch session summary[/bold]")
+    _stderr.print(f"  Polls: {stats.polls}")
+    _stderr.print(f"  Tweets seen: {stats.tweets_seen}")
+    for t in targets:
+        count = stats.per_user.get(t.username, 0)
+        _stderr.print(f"  @{t.username}: {count} new tweets")
+
+
+def watch_loop(
+    client: XApiClient,
+    targets: list[WatchTarget],
+    interval: int,
+    filters: list[str],
+    notify: bool,
+    max_tweets: int | None,
+    mode: str,
+    verbose: bool,
+) -> None:
+    """Main polling loop. Runs until Ctrl+C or max_tweets reached."""
+    stats = WatchStats()
+
+    # Seed last_seen_id for each target so we skip existing tweets
+    _stderr.print("[dim]Initializing watch...[/dim]")
+    for target in targets:
+        _seed_last_seen(client, target)
+        _stderr.print(f"[dim]  Tracking @{target.username} (id={target.user_id})[/dim]")
+
+    usernames = ", ".join(f"@{t.username}" for t in targets)
+    _stderr.print(f"[bold green]Watching {usernames}[/bold green] (every {interval}s, Ctrl+C to stop)")
+    if filters:
+        _stderr.print(f"[dim]Filters: {', '.join(filters)}[/dim]")
+    _stderr.print()
+
+    try:
+        while True:
+            for target in targets:
+                try:
+                    data = client.get_timeline(
+                        target.user_id,
+                        max_results=10,
+                        since_id=target.last_seen_id,
+                    )
+                except RateLimitError as e:
+                    reset_ts = e.reset_at
+                    try:
+                        wait = max(0, int(reset_ts) - int(time.time())) + 5
+                    except ValueError:
+                        wait = 60
+                    _stderr.print(f"[yellow]Rate limited. Waiting {wait}s...[/yellow]")
+                    time.sleep(wait)
+                    continue
+                except RuntimeError as exc:
+                    _stderr.print(f"[red]Error for @{target.username}: {exc}[/red]")
+                    continue
+
+                tweets = data.get("data", [])
+                if not tweets:
+                    continue
+
+                includes = data.get("includes", {})
+
+                # Tweets come newest-first; process oldest-first for chronological output
+                for tweet in reversed(tweets):
+                    text = tweet.get("text", "")
+                    note = tweet.get("note_tweet", {})
+                    if note and note.get("text"):
+                        text = note["text"]
+
+                    if not _matches_filters(text, filters):
+                        continue
+
+                    # Build a single-tweet payload for the formatter
+                    payload: dict[str, Any] = {
+                        "data": tweet,
+                        "includes": includes,
+                    }
+                    format_output(payload, mode, f"@{target.username}", verbose=verbose)
+
+                    if notify:
+                        _notify(target.username, text)
+
+                    stats.tweets_seen += 1
+                    stats.per_user[target.username] = stats.per_user.get(target.username, 0) + 1
+
+                    if max_tweets and stats.tweets_seen >= max_tweets:
+                        _stderr.print(f"\n[bold]Reached --max {max_tweets} tweets.[/bold]")
+                        _print_summary(stats, targets)
+                        return
+
+                # Update cursor to newest tweet
+                target.last_seen_id = tweets[0]["id"]
+
+            stats.polls += 1
+            time.sleep(interval)
+
+    except KeyboardInterrupt:
+        _print_summary(stats, targets)
diff --git a/tests/test_watch.py b/tests/test_watch.py
new file mode 100644
index 0000000..ac1a93b
--- /dev/null
+++ b/tests/test_watch.py
@@ -0,0 +1,59 @@
+"""Tests for watch module."""
+
+from x_cli.watch import _matches_filters, WatchTarget, WatchStats
+
+
+class TestMatchesFilters:
+    def test_no_filters_matches_everything(self):
+        assert _matches_filters("any text here", []) is True
+
+    def test_single_filter_match(self):
+        assert _matches_filters("Big $NVDA sweep today", ["$NVDA"]) is True
+
+    def test_single_filter_no_match(self):
+        assert _matches_filters("Big $TSLA sweep today", ["$NVDA"]) is False
+
+    def test_case_insensitive(self):
+        assert _matches_filters("nvidia is pumping", ["NVIDIA"]) is True
+        assert _matches_filters("NVIDIA is pumping", ["nvidia"]) is True
+
+    def test_multiple_filters_any_match(self):
+        assert _matches_filters("$NVDA calls", ["$TSLA", "$NVDA"]) is True
+
+    def test_multiple_filters_none_match(self):
+        assert _matches_filters("$AAPL calls", ["$TSLA", "$NVDA"]) is False
+
+    def test_partial_match(self):
+        assert _matches_filters("Something about flow", ["flow"]) is True
+
+    def test_empty_text(self):
+        assert _matches_filters("", ["keyword"]) is False
+        assert _matches_filters("", []) is True
+
+
+class TestWatchTarget:
+    def test_defaults(self):
+        t = WatchTarget(username="CheddarFlow", user_id="123")
+        assert t.username == "CheddarFlow"
+        assert t.user_id == "123"
+        assert t.last_seen_id is None
+
+    def test_with_last_seen(self):
+        t = WatchTarget(username="test", user_id="456", last_seen_id="789")
+        assert t.last_seen_id == "789"
+
+
+class TestWatchStats:
+    def test_defaults(self):
+        s = WatchStats()
+        assert s.tweets_seen == 0
+        assert s.polls == 0
+        assert s.per_user == {}
+
+    def test_accumulate(self):
+        s = WatchStats()
+        s.tweets_seen += 3
+        s.polls += 1
+        s.per_user["CheddarFlow"] = 3
+        assert s.tweets_seen == 3
+        assert s.per_user["CheddarFlow"] == 3