Poor social problem-solving has been shown to be associated with vulnerability, distress, and suicidality in young prisoners. The objectives of this study were to compare the social problem-solving abilities of vulnerable adult prisoners and those who are coping better with imprisonment, and to examine the effectiveness of a social problem-solving intervention, Stop & Think!, with a sub-group of vulnerable prisoners. Scores on the Social Problem Solving Inventory--Revised (SPSI-R) were compared for adult prisoners on normal location (n = 47) and those on a special landing for vulnerable prisoners (n = 68). Pre- and post-treatment scores on the SPSI-R were compared for 28 vulnerable prisoners who participated in Stop & Think! The data indicate that vulnerable prisoners are poorer social problem-solvers than those who are coping with imprisonment; that Stop & Think! appears acceptable to vulnerable prisoners and the staff who work with them and is practically applicable on a special landing; and that Stop & Think! may effect positive change in social problem-solving abilities. (PsycINFO Database Record (c) 2016 APA, all rights reserved)