Kleidemos of Athens wrote, perhaps after 378/7, a Protogonia (or Atthis), extending from mythical age up to 415 at least (§ 1-2). Several of the 27 sure fragments have been preserved by late lexicographers or erudites, but approximately half of them are quoted by four 2nd century authors (Harpocration, Athenaeus, Pausanias, Plutarch): it is disputed whether any of those four scholars directly read Kleidemos’ original text; in my opinion, at least Plutarchs probably did (§ 3). In any case, the main debate about Kleidemos concerns political tendency: Jacoby and many other scholars perceive a democratic bias in the preserved fragments, whereas Harding and others oppose this interpretation. In effect a careful reading of the historical fragments (mainly F 17-18 about Theseus; F 15 about Peisistratus; F 7-8 about Kleisthenes; F 21 about Themistokles; F 22 about the battle of Plataea; F 10 about an omen against the departure of the Sicilian expedition) suggests a democratic bias affecting strictly historical passages, as well as a democratic interpretation of events pertaining to mythical ages. Unfortunately it is impossible to determine whether this democratic attitude was a peculiar, extensive character of Kleidemos’ Atthis, or only episodic in its manifestation; nor it is easy to understand what kind of democracy Kleidemos intended to praise with his work, although he apparently appreciates a moderate conduct in foreign policy, perhaps in a Thrasybulian manner (§ 4-5).