Broad social identities like ethnicity and class are not only resources mobilized by social movements. Relational analysis reveals they can also be barriers constraining movement growth, as symbolic affinities with particular social identities may construct movement membership and support as incompatible with other identities. This mechanism may reproduce the particular demographics of social movements regardless of their universal messages and aspirations. Strategic deidentification may be crucial in struggles for social change. A study of the Israeli vegan animal advocacy movement during a time of diversification and growth is used to explore strategies movements use to dissociate themselves from particular social identities, both at the movement strategy level and the individual identity work level. Several 'deidentification strategies' are identified, including celebrating untypical identities, redefining the boundaries of the political, revising tactics and collective action frames, and becoming a field to mirror social space.