How does activists' knowledge predict the sustainability of a social movement organization? I answer this question using 4.5 years of full participation and activist ethnography in three distinct versions of the South Bend, Indiana chapter of the Black Lives Matter Global Network (BLMSB 1.0, 2.0, and 3.0). My participation in this nascent organization helped me develop a theory of knowledge convergence using an activist knowledge framework to explain variation between the three versions. The theory suggests that activists enter organizations with preexisting understandings of the world which they deploy collectively towards understanding the issues at hand. I found that activists predominantly drew on one of four knowledge sources (local-experiential, local-theoretical, global-experiential, global-theoretical) which I called their default. To sustain the organization, I argue that activists deploy their default knowledge towards bringing everyone into a central knowledge convergence zone.Chapter three investigates BLMSB 1.0 and addresses the question, "why did BLM-South Bend die?" I argue that even without White people, White supremacy infiltrated the organization. A knowledge hierarchy developed that privileged those with global-theoretical knowledge, which was positioned closer to whiteness, and doomed any attempts at knowledge convergence. Chapter four investigates BLMSB 2.0 to answer the question, "how did activist knowledge contribute to BLM-South Bend's reemergence and sustainability?" Toward this end, I introduce the concept of a frame anchor. Some issues can be so important that they anchor all activists' knowledge which legitimizes all four sources. This can expedite the knowledge convergence process.In chapter six, I answer the question, "why is it difficult to organize when resources and opportunities are abundant?" I argue that six problems (three concerning the political opportunity and three concerning the influx of resources) destabilized BLM-South Bend's knowledge convergence. Therefore, not only did the activists work to capitalize from the political opportunity but also needed to reestablish knowledge convergence.Overall, knowledge is an important social movement activism dimension that has largely been ignored in the scholarship. My focus on activists' knowledge digs into many of the process that social movement scholars take for granted and provides a framework for activists to sustain their nascent organizations.