Life course theory (LCT) diagnoses childhood and adolescent factors that determine an individual’s involvement in crime in the future. Farrington lists eight key correlates identified by empirical analyses of criminal careers. In this paper, we seek to discuss the inconsistencies with LCT that we observed in our three empirical studies of the criminal careers of Polish offenders. During 12 years of qualitative research, we conducted direct observations and in-depth interviews in juvenile correction institutions (21) and prisons (8) across the country. We gained access to incarcerated (102) and released (30) juvenile offenders, as well as to incarcerated (68) and released (28) adult offenders. We also conducted in-depth interviews (92) with experts working with young and adult offenders. We similarly accessed some offenders’ criminal records and psychological opinions. Our study revealed the strong presence of family and neighborhood influences on early criminality. Contrary to LCT assumptions, state-dependent institutions (military, work, family) were not strong enough determinants of delinquency. Polish offenders generally experience criminal onset later than LCT-oriented criminologists indicate. Based on our data, we also agree with the thesis that the onset of crime should be discussed as different age-related periods rather than just a general onset.