Selection, opportunity and learning have been proposed as possible mechanisms linking adolescents’ offending to that of their peers. This study tests competing hypotheses derived from these theoretical accounts, focusing on the so far unresolved question of the context specificity of peer effects. I investigate whether offending behaviour by the peer group of adolescents shown in one context is related only to adolescents’ own offending in the same context or also to offending in other contexts. Using data from the Edinburgh Study of Youth Transitions and Crime and applying random intercepts logistic regression models, I find evidence for context-specific peer effects of theft in different contexts. Peers’ self-reported theft in any context is related to adolescents’ self-reported theft in the same context but, with one exception, not to adolescents’ theft in other contexts. These results support learning as an important mechanism explaining peer similarity in offending, possibly alongside opportunity, while contradicting selection as an alternative explanation. Theoretically, the article argues for complementing learning theories with situational theories of action to obtain a more comprehensive picture of what adolescents learn from their peer group.