Why does people’s crime involvement vary and change? Developmental and Life-Course criminology has brought individual change to the forefront of criminological study and has done an impressive job of mapping out peoples age-graded patterns of crime involvement and demonstrated an abundance of individual and social factors correlated with various aspects of people’s criminal careers and their characteristics. However, DLC criminology has been less successful in comprehensively explaining the identified patterns and their correlates. In this paper I shall discuss some of DLC criminology’s theoretical shortcomings, specifically the limitations of the commonplace risk factor approach to explanation and the related idea of cumulative risk. I shall argue that criminal careers are best understood and analysed as a series of situationally caused crime events, putting the explanatory focus on the socially and age-graded stability and change in crime relevant situational factors, and, crucially, the developmental processes that drive continuity and change in these factors (the causes of the causes). All this is discussed based on Situational Action Theory (SAT) and its Developmental-Ecological-Action model (DEA model).