Personal initiative is conceptualized as a behavioural syndrome made up of several factors. It is important for organizational effectiveness and is one aspect of ‘contextual performance’. The construct validity of a set of interview- and questionnaire-based scales for measuring initiative was ascertained in interrelated studies (two waves from a longitudinal study in East Germany [N = 543] and a cross-sectional study in West Germany [N = 160]). As hypothesized, initiative correlated with partners' assessments, need for achievement, action orientation, problem-focused and passive emotion-focused coping, career planning and executing plans, but not with job satisfaction. Higher initiative existed in small-scale entrepreneurs in the East and in those unemployed who got a job more quickly.