This dissertation aims to address frequent calls for partnerships between informal science learning spaces and formal K-12 science education (e.g. Bevan & Dillon, 2010; Hofstein & Rosenfeld, 1996; NRC, 2009; Stocklmayer et al., 2010) as well as how informal educators and organizations are or are not addressing issues of equity within these types of partnerships. Informal science education (ISE) as a field is very broad, including such activities and contexts as public and family trips to places like museums and nature centers, K-12 school field trips, engagement with science media and more. Although millions of people visit informal science institutions each year (NRC, 2009), there is inequity in who can access these science experiences and for whom the experiences are designed. Partnerships between ISE institutions and schools are one potential way of both enhancing and supplementing school science as well as increasing participation in informal science experiences. Though many scholars call for these types of partnerships, there is little agreement about what kind of features might contribute to a successful and productive partnership. Another aim of this dissertation is to give a voice to informal science educators. Informal science educators (ISErs) are part of the science learning ecosystem but are often not considered in teacher education research. They come from a variety of educational backgrounds and therefore do not have common educational experiences. While a lot of teacher education research focuses on preservice teacher education programs and the potential of those spaces to work with future teachers to think about equity and social justice, there are not equivalent spaces where ISErs might engage in these same discussions. Therefore, it is important to see what kinds of knowledge and experiences ISErs have around DEI issues so that we might begin to think about the professional development needs they might have. This work addresses these problem spaces in three related papers. The first is a theoretical exploration of informal-formal science education partnerships. Because such partnerships involve two separate institutions with their own objectives, cultures, histories, and communities, I decided to explore the idea of partnerships through the lens of Cultural Historical Activity Theory (CHAT), which specifically takes into consideration how culture and history may affect human activity. In this first paper I will explain why CHAT is a useful lens through which to think about partnerships as well as provide recommendations for how to create productive partnerships based on this theoretical framework. The second manuscript is a narrative case study of a partnership in formation between a local park system and a public school within a large urban school district in a midwestern state from the perspective of two ISErs. This paper describes in detail the challenges and successes of creating a partnership between two very different systems and the learning that was required of the informal educators to work productively with teachers and students in an urban school context. I will show how CHAT played out in action for these educators including what aspects were instantiated in their work and what was missing that might have contributed to challenges they experienced. The third and final manuscript is a survey and interview study with ISErs who work, at least in part, with K-12 students in urban areas. It focuses on their perceptions around issues of diversity, equity, and inclusion (DEI), what efforts they and their organization have made regarding DEI, whether their organizations are supportive or not when it comes to further efforts, and what barriers they feel exist to making change at their organization or the field. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]