The objective of this study was to describe associations between childhood factors and adult daily substance use profiles among homeless women and to identify independent predictors of daily substance use for the overall sample and for ethnic/acculturation subgroups. Structured surveys were administered to 1,331 homeless women in Los Angeles who were either daily drug and alcohol users for the past 6 months or nondaily substance users. Physical abuse and parental drug abuse predicted daily drug use in the whole sample and selected subgroups, whereas parental alcohol abuse predicted daily alcohol use in the whole sample. Teen self-esteem was also found to have a protective effect on daily alcohol use for the sample and for African American women. Negative peer influence in adolescence predicted daily drug use among high-acculturated Latinas. In summary, childhood abuse, parental substance use, and negative peer influence affect important roles in homeless women's daily substance use.