To our knowledge, the present study is the first randomized trial in a substance use population in which the central target of the treatment was shame. A 6-hr group using an ACT approach to shame as a small part of a 28-day residential program led to slower immediate gains in shame but better long-term progress. The slower posttreatment gains in the ACT group compared to TAU were not predicted but were made sense of by subsequent analyses. Results indicated that reductions in shame during active treatment predicted higher levels of substance use at follow-up. Mediational analyses suggested that the more gradual reductions in shame found in the ACT group protected against the pattern seen in TAU for shame reductions to be associated with subsequent higher levels of substance use. As predicted, the ACT intervention led to higher levels of outpatient treatment attendance during follow-up, which in turn were functionally related to lower levels of substance use. Across the board, participants in the ACT condition showed a pattern of continuous treatment gains, especially on psychosocial measures, rather than the boom and bust cycles seen in TAU.
