Diffusion in a vacuum: edTPA, legitimacy, and the rhetoric of teacher professionalization

•edTPA diffusion is attributable to distributed governance structures and flexible rhetoric.•Researchers and professional associations were instrumental in facilitating adoption of edTPA.•Advocates rhetoric drew on the indeterminate meaning of calls for “greater accountability”.•Findings are organizational theory predictions on role of professional organizations.•Findings suggest evolving meaning of “accountability” and “professionalization”.