The dyadic adjustment and substance use of couples with a drug-abusing husband (n = 94), couples with a drug-abusing wife (n = 36), couples in which both partners abused drugs (n = 87), and non-substance-abusing conflicted couples (n = 70) were examined. For couples with 1 drug-abusing partner, a higher percentage of days abstinent during the year before treatment for drug abuse was associated with a higher level of relationship satisfaction. When both partners abused drugs, the relationship between percentage of days abstinent and relationship satisfaction became stronger and more negative as the time partners spent together using drugs increased. A higher percentage of days abstinent was associated with relationship stability for couples with 1 drug-abusing partner during and 1 year after treatment; for couples in which both partners abused drugs, a higher percentage of days abstinent was associated with relationship instability.