There is a paucity of research examining substance abuse issues among women prisoners. This study explored relationships between perceived stress, impulsivity, and beliefs in the efficacy of drugs as these variables pertain to self-reported drug use severity. Women prisoners (N = 100) participated in structured face-to-face interviews based on established research instruments. Although there was no significant correlation between demographic characteristics and substance use severity, positive relationships were found between substance use severity, perceived stress, impulsivity, and beliefs. A multiple linear model was estimated regressing drug use severity on beliefs, impulsivity, and perceived stress. Only the measures of beliefs and impulsivity were significant correlates of drug use severity. Implications are discussed for prison substance abuse programming and future research.