The explosion of new social network technologies has highlighted the awkward relationship between new "Twenty-first century" media practices and existing educational systems. Traditional content standards, achievement tests, and accountability pressures threaten nascent efforts to foster equitable, transparent, and credible participation in these practices. The current push to design external tests and standards to assess these new practices may actually exacerbate this problem, due to the fundamentally social nature of these proficiencies. Large-scale standardization and testing of aggregated achievement of these proficiencies should be done cautiously and in isolation from classroom-based efforts to foster worthwhile participation. Likewise, within classrooms, more interpretive efforts are first needed to define social contexts that foster worthwhile social participation in these practices before individual proficiency is assessed. To foster both participation and proficiency while also meeting existing and future accountability goals, a design-based participatory assessment framework with multiple levels of increasingly formal outcomes is introduced.Keywords Formative assessment · Social media · Twenty-first century skills New media technologies are resulting in new communities based on new forms of communication, learning, and self-expression Shirky, 2008). Many of these communities are organized around creative expressions, including traditional expressions (e.g., AllPoetry) and newly popularized forms of traditional expressions (e.g., fan fiction at FictionAlley and music remixes at ccMixter). 1 These communities exemplify "affinity spaces" (Gee, 2004) that feature low barriers to entry, support for creating and sharing, informal mentoring of newcomers, and a strong sense of social connection. Media scholar Henry Jenkins and his colleagues D.T. Hickey (B) Learning Sciences Program, Indiana University, Bloomington, IN, USA e-mail: dthickey@indiana.edu 1 For convenience and space considerations, references will be omitted throughout for resources that can be readily identified and located via popular search engines.