This methodological investigation examines the accuracy of narrative-based scaled ratings covering several post high school years. Guided narratives by young adults described developmentally relevant behaviour and context for each month between ages 17 and the mid-20s. "Prospective" narratives covered shorter time periods in three interviews separated by about 1 year each. A fourth "retrospective" interview included the entire period covered in the previous narratives and took place 1 year after the last prospective interview. Study variables were reliable ratings of data from these carefully conducted and blindly repeated narratives. Aspects of the study design expected to maximise reliability and validity of these data are provided. Prospective-retrospective (test-retest) correlation of ratings based on data from 149 participants covering an average of 64 studied months each on role-related, qualitative, and social variables are reported. The high consistency of many developmental variables based on these reports suggests that retrospective narratives can produce reliable and valid scaled measures covering a substantial period of time. (Contains 3 tables, 1 figure, and 4 footnotes.)