This study compared the characteristics of probability samples of homeless adults in Poland (N = 200 from two cities) and the United States (N = 219 from one city), using measures with established reliability and validity in homeless populations. The same measures were used across nations and a systemic translation procedure assured comparability of measurement. The two samples were similar on some measures: In both nations, most homeless adults were male, many reported having dependent children and experiencing out-of-home placements when they themselves were children, and high levels of physical health problems were observed. Significant national differences were also found: Those in Poland were older, had been homeless for longer, showed lower rates on all psychiatric diagnoses assessed (including severe mental and substance abuse disorders), reported less contact with family and supportive network members, were less satisfied when they sought support from their networks, and reported fewer recent stressful life events and fewer risky sexual behaviors. Culturally-informed interpretations of these findings and their implications are presented.