A sample of college students (N=170) was used to replicate and extend recent investigations that had conceptualized adults' close relationships within an early attachment framework. Analyses were conducted to support the validity of Hazan and Shaver's (1987) attachment measures, which were designed to assess the three major styles of attachment: secure, anxious/ambivalent, and anxious/avoidant. The Single-Item, Multi-Item, and Mental Model attachment measures were also used to test the association between young adult attachment and psychosocial adjustment. Results showed that using a self-classification measure appears to be a valid method of assessing young adult attachment. Furthermore, findings revealed a strong relation between mental models and attachment style, demonstrating construct validity for this assessment of internal working models. Finally, attachment characteristics were found to be strongly related to psychosocial adjustment. The secure group had more positive mental models and were better adjusted overall. Few differences emerged between the anxious/ambivalent and anxious/avoidant groups. This result is consistent with findings from infant attachment studies. (Four data tables and references are included.) (Author/ABL)