The article examines the problem of verbal typology of a diary. Based on the criterion of goal-setting, the types of verbal behavior of a diary author are established, and language features that define the characteristics of the text of the genre in whole, as well as its specific variations, are analyzed. These varieties are determined by the priority in diary activities, contributing an informative, emotional-introspective, rational-logical and pictorial type of verbal behavior. The type of verbal behavior is the basic and the most general manifestation of a personality in the text of a diary, defining particular individual language traits. The examination is exemplified through a case-study of the diaries of G.Efron, S.I.Vavilov and K.I.Chukovskiy.