The purpose of this study was to explore the ways in which in-service physical education teachers construct their self-efficacy beliefs toward teaching students with disabilities in general physical education classes. Using a qualitative descriptive approach situated within self-efficacy theory, data were collected via semistructured audio-recorded interviews with 16 in-service physical educators. Three interrelated themes were constructed: (a) The more I do it, the better I feel: the importance of professional experiences; (b) I’ve learned from others: the influence of colleagues; and (c) Being in the general educational setting is a challenge: the impact of contextual factors. Findings supported the influence of the four sources of self-efficacy (i.e., mastery experience, vicarious experience, social persuasion, and affective and physiological state), in addition to potential contextual factors (i.e., class sizes and availability of hands-on support), impacting participants’ self-efficacy to teach students with disabilities in general physical education classes.