In recent decades, digital technologies have facilitated new opportunities for educators to share and co-construct teaching and learning ideas and resources. One largely unresearched example of this phenomena is HyperDocs, which are interactive, digital teaching and learning materials created, disseminated, and remixed by educators. Despite indications of significant HyperDoc use, little is known regarding how educators learn about and develop in their use of HyperDocs. To address this gap in the literature, we collected self-report survey data from 261 HyperDoc-using educators. Participants learned about HyperDocs in both traditional professional development contexts and in more informal and self-directed activities. Different people, spaces, and tools played roles in the participants becoming knowledgeable about and refining their use of HyperDocs. We discuss our findings in relation to research on professional learning networks and crowdsourced approaches to teaching and learning.