Participants were given structured questionnaires at two points in time by trained, ethnically matched interviewers. Pearson correlation coefficients and hierarchical regression analyses were done to examine relationships among psychosocial factors and needle-sharing at the first time point and the relationships of prior needle-sharing and unconventionality, poor emotional control, and poor intrapsychic functioning on needle-sharing at the second time point. Results revealed that the psychosocial protective factors at the first time point buffered the relationship between needle-sharing at the two time points. Findings supported a mediational model in which personality and peer factors predicted the initial needle- sharing, which served as the mediator for later needle- sharing. Tables and 44 references (Author abstract modified)