Many Athenian magistrates, including the Secretaries, were taken from the several tribes in cycles following their official order. These Tribal Cycles, first discovered by the author in 1898, serve during the Hellenistic Age as the basis for establishing the list of annual archons by means of which the sequence of events is fixed. For the periods before 262 B.C. and after 145 B.C. the author accepts the cycles constructed by Professor Dinsmoor in his recent book on The Archons of Athens in the Hellenistic Age. He rejects those for the intervening period and adduces new evidence to sustain an alternate scheme of cycles. Besides furnishing a more exact chronology for the history of Athens during the Macedonian epoch, the monograph contains epigraphical and historical interpretations of numerous documents and throws fresh light upon the theory and practice of Athenian democracy.