This investigation examined the impact that instructor out-of-class support (OCS) and sex differences have on students’ perceptions of instructor credibility. Participants (N = 634) were randomly assigned to one of six experimental conditions manipulating the degree to which an instructor responds with a highly supportive, moderately supportive, or non-supportive message following a hypothetically stressful situation. Multivariate analyses revealed a two-way interaction effect of instructor OCS by student sex on perceptions of instructor credibility. Significant and meaningful main effects for instructor OCS on all three dimensions of credibility (i.e., competence, trustworthiness, and caring) were also obtained, with students attributing more credibility to highly supportive instructors than to instructors who provide only moderate or no messages of support