diff --git a/bibtexparser/model.py b/bibtexparser/model.py
index 3e93f63..421aef9 100644
--- a/bibtexparser/model.py
+++ b/bibtexparser/model.py
@@ -378,7 +378,12 @@ def get(self, key: str, default=None) -> Optional[Field]:
         return self.fields_dict.get(key, default)
 
     def __contains__(self, key: str) -> bool:
-        """Dict-mimicking ``in`` operator."""
+        """Dict-mimicking ``in`` operator.
+
+        As in ``__getitem__``, ``ENTRYTYPE`` and ``ID`` are always contained.
+        """
+        if key in ("ENTRYTYPE", "ID"):
+            return True
         return key in self.fields_dict
 
     def __getitem__(self, key: str) -> Any:
@@ -400,8 +405,16 @@ def __setitem__(self, key: str, value: Any):
 
         This serves for partial v1.x backwards compatibility,
         as well as for a shorthand for `set_field`.
+
+        Mirroring ``__getitem__``, the keys ``ENTRYTYPE`` and ``ID``
+        set ``entry_type`` and ``key`` instead of a field.
         """
-        self.set_field(Field(key, value))
+        if key == "ENTRYTYPE":
+            self.entry_type = value
+        elif key == "ID":
+            self.key = value
+        else:
+            self.set_field(Field(key, value))
 
     def __delitem__(self, key: str) -> None:
         """Dict-mimicking index.
diff --git a/tests/test_model.py b/tests/test_model.py
index 497fce4..c00929e 100644
--- a/tests/test_model.py
+++ b/tests/test_model.py
@@ -96,6 +96,30 @@ def test_entry_contains():
     entry = Entry("article", "key", [Field("field", "value", 1)], 1, "raw")
     assert "field" in entry
     assert "other" not in entry
+    # ENTRYTYPE and ID are exposed by `__getitem__`, hence always contained
+    assert "ENTRYTYPE" in entry
+    assert "ID" in entry
+
+
+def test_entry_setitem_field():
+    entry = Entry("article", "key", [Field("field", "value", 1)], 1, "raw")
+    entry["field"] = "new_value"
+    entry["other"] = "other_value"
+    assert entry["field"] == "new_value"
+    assert entry["other"] == "other_value"
+    assert [f.key for f in entry.fields] == ["field", "other"]
+
+
+def test_entry_setitem_entrytype_and_id():
+    entry = Entry("article", "key", [Field("field", "value", 1)], 1, "raw")
+    entry["ENTRYTYPE"] = "book"
+    entry["ID"] = "new_key"
+    assert entry.entry_type == "book"
+    assert entry.key == "new_key"
+    assert entry["ENTRYTYPE"] == "book"
+    assert entry["ID"] == "new_key"
+    # No literal fields must be created for these keys
+    assert [f.key for f in entry.fields] == ["field"]
 
 
 def test_string_equality():