The research design aimed to enable researchers to study individual development over a long interval of the lie course by gathering data during a comparatively short interval of time. Such designs also create possibilities not available in standard panel designs for separating developmental effects from cohort and period effects. However, such designs require complex statistical analysis and pose several inferential challenges to researchers. The research used data from two cohorts of the National Youth Survey, each of which was observed for only 5 years. One cohort was followed from ages 11 to 15, while the other was followed from ages 11 to 18. Results revealed that both the expected level of deviance and the rate of change of deviance were similar across the two cohorts at the points where their data overlap. Both an inflection point (the age at which the rate of increase in pro-deviant attitudes begins to slow down) and a peak age (the age of maximum pro- deviant attitude) were found. Tables, figures, notes, and 21 references (Author abstract modified)