There are no prospective studies that have investigated the effects of an intervention to improve end of life (EOL) care in an underserved population. To determine whether homeless persons will complete an advance directive (AD). Randomized trial comparing two modes of providing an opportunity for homeless persons to complete an AD. Half of the subjects were randomized to a self-guided group (SG) who were given an AD and written instructions; the other half were given the same material but, in addition, were offered the opportunity to receive guidance to complete the AD (CG). Fifty-nine homeless persons recruited from a drop-in center. Rate of AD completion and baseline and 3-month follow-up EOL-related knowledge, attitudes, and behaviors. The overall AD completion rate was 44%, with a statistically significant higher completion rate of 59% in the CG group compared to 30% in the self-guided only group. Frequency of worry about death decreased among those who filled out an AD from 50% to 12.5%, and also among those who did not (25% to 12.5%) (p < .05). Among those who filled out an AD, there were increases in plans to write down EOL wishes (56% to 100%; p < .05) and plans to talk about these wishes with someone (63% to 94%; p < .05). This study demonstrates that people living in dire economic and social situations will complete an AD when offered the opportunity. While offering guidance resulted in higher rates of completion; even a simple self-guided AD process can achieve completion of ADs in this population.