In the first part of this paper, I shall argue that Apollodorus of Athens, in his Chronica, dated Anaxagoras' arrival at Athens to 456/5, following Demetrius of Phalerum (Record of Archons). Rejecting the divergent opinion of others, he also followed Demetrius' estimation of the Athenian period as having lasted 20 years, which makes 437/6 Anaxagoras' last year at Athens 1). In the second part I shall argue that the trial of Anaxagoras, about which no information survives in the remains of Apollodorus but which is reported by several other sources, should probably be dated to 437/6. This second argument is independent of the first; both run counter to the view, still rather popular among historians of ancient philosophy, which favours a date for the trial either immediately preceding or even following upon the beginning of the Peloponnesian War (spring 431 B.C.), as well as to the communis opinio according to which the Athenian period lasted 30 years. What is common to both parts of this inquiry is a refusal to study the chronology of Anaxagoras' career in isolation. In part I, which is chiefly concerned with an analysis of the relevant passage in Diogenes Laertius qua specimen of Apollodorean reasoning, the problem is discussed against the background of Apollodorus' synchronistic matrices. In part II, the trial and the decree of Diopeithes which made it possible are studied in connection with the plot against Pericles and certain members of his circle.-A suggestion regarding the date of 'publication' of Anaxagoras' treatise will be appended to part II.