diff --git a/app/models/activity.py b/app/models/activity.py
new file mode 100644
index 0000000..b013841
--- /dev/null
+++ b/app/models/activity.py
@@ -0,0 +1,77 @@
+"""Activity model: calls, meetings, emails, tasks, notes tied to any entity."""
+
+from __future__ import annotations
+
+from datetime import datetime
+from enum import Enum
+from typing import TYPE_CHECKING, Optional
+
+from sqlalchemy import DateTime, ForeignKey, String, Text
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import Base, OrgScopedMixin, SoftDeleteMixin, TimestampMixin
+
+if TYPE_CHECKING:
+    from app.models.user import User
+    from app.models.account import Account
+    from app.models.contact import Contact
+    from app.models.deal import Deal
+
+
+class ActivityType(str, Enum):
+    """Type of activity."""
+
+    call = "call"
+    meeting = "meeting"
+    email = "email"
+    task = "task"
+    note = "note"
+
+
+class Activity(Base, TimestampMixin, SoftDeleteMixin, OrgScopedMixin):
+    __tablename__ = "activities"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    type: Mapped[ActivityType] = mapped_column(
+        String(32), nullable=False, index=True
+    )
+    subject: Mapped[str] = mapped_column(String(255), nullable=False)
+    body: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
+    due_date: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True, index=True
+    )
+    completed_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )
+    account_id: Mapped[Optional[int]] = mapped_column(
+        ForeignKey("accounts.id"), nullable=True, index=True
+    )
+    contact_id: Mapped[Optional[int]] = mapped_column(
+        ForeignKey("contacts.id"), nullable=True, index=True
+    )
+    deal_id: Mapped[Optional[int]] = mapped_column(
+        ForeignKey("deals.id"), nullable=True, index=True
+    )
+    owner_id: Mapped[int] = mapped_column(
+        ForeignKey("users.id"), nullable=False, index=True
+    )
+
+    # Relationships
+    account: Mapped[Optional["Account"]] = relationship(
+        "Account", back_populates="activities", lazy="selectin"
+    )
+    contact: Mapped[Optional["Contact"]] = relationship(
+        "Contact", back_populates="activities", lazy="selectin"
+    )
+    deal: Mapped[Optional["Deal"]] = relationship(
+        "Deal", back_populates="activities", lazy="selectin"
+    )
+    owner: Mapped["User"] = relationship(
+        "User", foreign_keys=[owner_id], lazy="joined"
+    )
+
+    def __repr__(self) -> str:
+        return f"<Activity id={self.id} type={self.type} subject={self.subject!r}>"
+
+
+__all__ = ["Activity", "ActivityType"]