The purpose of this study was to examine the relation between locus of control (LOC) and attributions of academic performance by the actor and by others. Three hundred and seventy-three undergraduate students completed a Likert-type version of the Locus of Control Scale (Collins. 1974), and a version of the Multidimensional Multiattributional Causation Scale (Lefcourt, von Bayer. Ware. & Cox. 1979), which described academic performance by self or university students in general. Subjects were divided into internal and external LOC groups. It was expected (a) that internal locus of control subjects would make use of effort in their explanations, and less use of luck than would externals; (b) that attributions of self performance by both internal and external LOC subjects would be more internal than attributions of others' performance, especially for success; (c) that, if an external control orientation is a defensive reaction, external LOC subjects would attribute failures more externally than successes; and (d) that internal LOC subjects would be less likely to use ability explanations than effort. The results generally supported all the hypotheses except the third, and were interpreted as supporting Rotter's (1966) view that LOC is an individual bias, independent of situational variables which influence attributions. Weiner's (1979) version of attribution theory was also supported. although the variable of controllability needs more research, particularly on the way it influences attributions to ability and task difficulty.