This study documents teachers' perceived impact of a massive open online course (MOOC) entitled The Self-Determined IEP: Supporting "Success for Students with Behavioural and Adjustment Difficulties" using Coldwell & Simkins' (2011) model for evaluating continuing professional development in education. Employing pre-experimental pretest post-test research design with no comparison or control group, the 55 participating teachers responded to four online questionnaires at pre-determined points over the course of the study. Findings indicate that, as regards self-determination and individualized education plan (IEP) implementation, teachers experienced significant growth in knowledge, an increased sense of self-efficacy in handling socially and behaviourally challenged children, and improved teacher practices. With few respondents having yet employed a self-determined IEP in the field, no definitive conclusions are available concerning student outcomes, however findings imply good potential. No significant shift in respondents' attitudes towards inclusive classrooms was noted. We discuss factors which contributed to findings in order to submit guidelines and possible avenues for future teacher training endeavours.