The findings showed that the common-factor model generally provided a better fit to the data than did the purely transmissional effects model. The results were inconsistent with regard to the strength and direction of the transmission effect. While the findings did not identify the variables responsible for the different causal processes, several non-mutually exclusive interpretations are offered. These include a trait disposition toward deviance behavior, including low self-control, or unchanging aspects of the social environments including concurrent sibling effects, common friends, or common opportunities for crime. A trait interpretation suggests the possibility of a genetic influence on delinquency. Future research could involve full-siblings raised apart or a comparison of adopted and non-adopted siblings. A more accurate investigation of an autoregressive, transmission process should involve longer intervals between measurements, permitting greater real change in delinquency. 4 tables, 2 figures, and 37 references