The Next Generation Library Publishing project (NGLP) seeks to expand the range of publishing pathways available for authors, editors and readers to distribute and access knowledge in ways that are compatible with academic values of openness and equity. In collaboration with the library publishing community, NGLP is developing tools and services that combine the values alignment of open source software with the convenience of turnkey publishing and repository solutions. This presentation will describe NGLP's approach to building interoperable open source software that leverages open metadata and protocols to enhance, rather than replace, widely adopted publishing platforms. We will explore how modular architecture, based on open standards, can empower library publishers to manage content in new ways, while promoting data portability and encouraging the development of sustainable and ethical service models. NGLP, a collaborative initiative of Educopia, California Digital Library, Strategies for Open Science (Stratos), and the Confederation of Open Access Repositories, is generously funded by Arcadia.