The article presents the results of the development and psychometric analysis of the new psychological Apathy Scale. In three consecutive studies, in which a total of 727 adult Russian-speaking respondents took part, convincing evidence of psychometric consistency of the scale was obtained. In the first study, a preliminary approbation of the Apathy Scale was done, which indicated a homogeneous and reproducible factor structure of the scale. In the second study, the reliability and validity of the Apathy Scale was evaluated. The Cronbach’s alpha coefficient was 0.85, and the differences between the mean apathy values measured during the test and retest were not statistically significant according to the Bland-Altman plot. Convergent and divergent validity of the scale was established by means of positive correlations of the scale with indicators of adolescent apathy, alienation from study, academic amotivation, alexithymia and social anhedonia, as well as negative correlations with indicators of student engagement, intrinsic cognition, achievement, personal growth, motivation for self-respect, introjected motivation and external regulation. The third study assessed the social desirability of the Apathy Scale. With the help of experimental manipulation with fake-good, standard and fake-bad instructions, as well as the analysis of correlations of the scale with the Paulhus’ Balanced Inventory of Desirable Responding, it was shown that the scale is stable and adequate in conditions of high social desirability. Based on the results of the study, it is concluded that the new psychological Apathy Scale is a reliable and valid instrument for the psychological assessment of apathy in adult Russian-speaking respondents.