The study examined the Implicit Relational Assessment Procedure’s (IRAP) validity as a computerized response-latency-based measure of implicit self- esteem. University undergraduates and 2 sets of convicted prisoners partici - pated. One set of prisoners resided in the main block, and the other in a privi - leged lower security “open area” of a medium-security Irish prison. The IRAP required participants to maintain relational responses that were self-positive on half of the IRAP trials (“Consistent”), and self-negative on the other half (“Inconsistent”). As predicted, the students and the prisoners in the open area showed stronger IRAP effects (shorter latencies during consistent vs. inconsis - tent trials) than the main block prisoners. Additionally, the IRAP’s convergent validity was supported by its moderate positive correlation with an explicit self-esteem measure. The findings provide preliminary support for the ana - lytic utility of the IRAP and suggest future avenues of investigation afforded by the IRAP’s design.