Despite policy mandates to include students with disabilities in educational assessment and accountability programs, current practices suggest a substantial lack of capacity for effective inclusion. Continuing professional development (CPD) is an essential component of disseminating and implementing effective inclusion practices. Recent reviews of CPD for teachers suggest traditional CPD methods are largely inef fective in changing practices. In this article, we identify features of CPD likely to lead to changes in teachers' practices and discuss how these features interact with the unique content and challenges related to inclusion to identify promising CPD practices. Evidence evaluating one CPD effort, Assessing One All, is presented to document the effectiveness of such CPD practices and to illustrate the benefits and barriers to effective CPD for inclusion in large-scale assessments. These findings provide a foundation for discussing how research can guide CPD efforts to enhance inclusion of students with disabilities in educational assessment and accountability programs. textcopyright 2005, Sage Publications. All rights reserved.