Life course theory focuses attention on the impact of history, timing, and important transitions in life trajectories. In this chapter, the life course analysis of boomer drug users reveals that drug trajectories were not developmental. Instead, they were discontinuous, interrupted phases dependent on social context and situations that changed over time. The chapter provides a closer inspection of the turning points into and out of drug use phases to better understand the causes of problematic drug use and what resources are needed to control it. In contrast to law enforcement and treatment professionals, who view problematic drug use as a lack of self-control, research finds that informal social control mechanisms are more important for maintaining or regaining control over drug use. Life course theory predicts that missing critical transitions in life, such as graduating from high school, leads to fewer informal social controls. The stories in this chapter reveal the negative impact of juvenile incarceration, which did not help anyone become drug free, but instead plunged youths into a criminal culture and broke their social bonds to mainstream social networks and access to informal social control mechanisms.