New Public Management (NPM) has added new aspects to the conflict between political-bureaucratic steering and professional autonomy in the search for a substance use treatment system (SUT) that is economic and characterized by high quality, accessibility, and professional discretion. This article analyses if and how organizational aspects of NPM imply additional challenges for professionals and SUT. The experiences of 29 social workers, in different positions in the services and administration of SUT, in six municipalities with different degrees of NPM and post-NPM, form the empirical data. Many quality problems were common across municipalities: frequent unevaluated reforms, lack of resources for SUT, and cooperation issues. Several problems were especially pronounced in statutory social work. NPM added challenges. Competition with private providers was viewed as initially (in the 1990s) having improved treatment, but the present market was regarded as creating quality problems without savings. Cooperation between providers was a special quality challenge in NPM municipalities, and NPM added to treatment continuity challenges. While accessibility for resourceful clients was linked to NPM models, treatment for less resourced users was obstructed by NPM. Workplace climate and trust issues were more problematic in the most NPM-permeated municipalities. Professional discretion was difficult to link to local NPM degree. Increased standardization and documentation were often accepted as improving quality. While a system based on competition ideology appeared destructive for treatment quality, post-NPM reforms with cooperation between needs-assessment, treatment, and economic support, conformed better with professionals' perceptions of good treatment.