The 'Communities & Crowds' project offers a new model for Gallery, Library, Archive and Museum (GLAM) institutions to engage more deeply with their audiences through their collections, both in-person and online. The goal of the project is ultimately to break down barriers, and engage new volunteer communities to interrogate and make visible heritage collections in collaboration with institutional structures. By combining participatory and citizen science methodologies throughout this project, the outcomes of this experimental program will have impact for both museum practice and concepts of digital-enabled participation. In cultural heritage organizations across the UK and US, volunteers are a critical part of institutional infrastructure. Volunteer labor is ubiquitous, spanning disciplines from art museums to planetaria. Within cultural organizations, volunteers interact with visitors, work with collections, and provide administrative support, among myriad other tasks that vary across institutions. Volunteers help to ensure that institutions run smoothly, even when budget limitations prevent the hiring of additional staff. At the same time, volunteers personally benefit from their association with museums, either due to interest in the content of collections, a feeling of 'giving back' to one's community, opportunities for socialization, or career-oriented learning and experience-building. As cultural institutions increasingly make use of digital technology to engage audiences, the need for volunteers has arisen in those spaces as well. However, digital volunteer opportunities often focus on volunteers as audiences, rather than as an essential part of the institutional team. One example of attracting digital volunteers to heritage institutions is through online crowdsourcing projects. Crowdsourcing is a form of digitally-enabled participation which invites volunteers to engage with institutional collections by performing meaningful tasks. It is often viewed as a way to simultaneously encourage public engagement with heritage materials, while completing essential institutional data processing tasks that can result in making collections searchable and discoverable by a wider range of audiences. However, most crowdsourcing projects are created 'offline' and only shared with online volunteers once the project's aims and research questions are fully formed. In this way, digital volunteers are assigned the role of 'users' or 'audience', rather than as co-creators or collaborators. In the 'Communities & Crowds' project we aim to re-examine the role of the volunteer in the physical and digital realms, with the ultimate goal of breaking down hierarchical barriers and providing a roadmap for teaching cultural institutions to use online engagement as a model for interacting with both digital and in-person volunteers as collaborators with institutional staff. In particular, we will focus on how this practice can be realized through the process of online crowdsourcing, using the Zooniverse platform as a case study. This collaborative effort will include researchers, curators, educational and volunteer teams at the National Science and Media Museum (Bradford, UK), the Zooniverse teams at the Adler Planetarium (Chicago, IL) and Oxford University (Oxford, UK), and online volunteers around the world.