Prison education is an important aspect of adult education. This study investigated current participation in prison education, as well as previous convictions, sentence length, and the portion of sentence served as predictors of academic self-efficacy. Survey data derived from prisoners in all Norwegian prisons provided the empirical evidence for the analyses. A principal component analysis of a 40-item academic self-efficacy questionnaire revealed self-efficacy components in literacy, mathematics, information and communications technology (ICT ), and self-regulated learning. Educational participation had a positive influence on self-efficacy in both mathematics and self-regulated learning. Participants who reported no previous convictions scored higher than others on self-efficacy in mathematics, self-regulated learning, and ICT. Furthermore, the results showed that perceived efficacy in ICT decreased with longer sentence length. Portion of sentence served was not significantly related to any of the four self-efficacy components. The findings are discussed with reference to a need for mastery experiences in prison and implications for policy and practice.