Summary: GAO discussed: (1) the current state of knowledge regarding drug abuse treatment; (2) what influenced the state of knowledge regarding drug abuse treatment; and (3) National Institute on Drug Abuse (NIDA) activities aimed at developing drug abuse treatment knowledge. GAO noted that: (1) while the nature of the drug abuse problem fundamentally changed during the past decade, drug abuse treatment knowledge advanced slowly; (2) significant gaps existed in understanding the relative effectiveness of existing treatments and in developing new treatments; (3) NIDA-funded research emphasized opiate abuse, although cocaine and crack abusers significantly outnumbered opiate abusers; (4) lack of large-scale evaluations of drug abuse treatment programs and existing methodological problems limited knowledge regarding drug abuse treatment effectiveness; (5) NIDA lacked a long-term strategic planning process, but planned to establish a strategic planning unit and an advisory board; (6) NIDA failed to involve treatment practitioners in decision-making regarding treatment research priorities; (7) low research budgets accounted in part for slow progress on treatment knowledge; and (8) NIDA funding for training drug abuse researchers lagged behind drug abuse research funding, resulting in slow progress in the development of drug abuse treatment knowledge.