Previous research suggests that writing about stressful experiences results in better health and psychological well-being. In the present study, a multi-ethnic sample of 79 HIV-positive women and men participated in a structured interview, and wrote about either their deepest thoughts and feelings about living with HIV (expressive writing) or their activities in the last 24 hr (control). Sixty-two participants returned for the 2-month follow-up and 50 returned for the 6-month follow-up interview. Oral fluid samples of beta2-microglobulin were taken at the baseline and follow-up assessments to examine the immunological effects of writing. No effects of writing condition were found, but expressive writing participants who included increasing insight/causation and social words in their writing had better immune function and reported more positive changes at follow-up. Results suggest that cognitive processing and changes in social interactions may be critical to the benefits of writing.