This article assesses the reliability and validity of the Cocaine Selective Severity Assessment (CSSA), a measure of cocaine abstinence signs and symptoms. Interrater reliability and scale internal consistency were high. Initial CSSA scores were significantly higher in cocaine-dependent subjects than in alcohol-dependent subjects. Initial CSSA scores were highly correlated with recent cocaine use and with severity measures from the Addiction Severity Index (ASI) including the interviewer severity rating and composite score in the drug section. Among cocaine-dependent subjects, initial CSSA scores were higher for those who failed to achieve abstinence or who subsequently dropped out of treatment. Further, CSSA scores showed consistent and marked declines over time for subjects who continued in treatment and remained abstinent. The CSSA appears to be a reliable and valid measure of cocaine abstinence symptoms and a useful predictor of negative outcomes in cocaine dependence treatment.