Every year the National Science Foundation (NSF] gathers together leadership teams of funded Math and Science Partnership programs (MSP) at a Learning Network Conference in Washington, D.C. The purpose of the annual conference is to bring together teams of MSP leaders who represent institution higher education (IHE] faculty from STEM disciplines, IHE education faculty, school partners, and project evaluators, to give them an opportunity to learn across projects, and provide opportunities for individual projects to reflect on their progress. For the last two years, 2011 and 2012, we were part of the conference's organizing committee. During the two-day conference, project teams were invited to articulate their theories of action for preparing teachers to be effective STEM teachers and to describe in broad strokes or in fine grain detail what was happening within their projects' professional development opportunities. Projects also had the opportunity to share within a public forum the preliminary, incomplete, or final results emerging from projects' evaluations or research efforts aiming to determine whether the MSP projects were deepening teachers' content and pedagogical knowledge, changing teachers' practices, and, ultimately, positively impacting students' success.While the Learning Network Conferences are intended to be for leaders within the MSP community, what MSPs are learning about STEM teaching and learning and professional development are worth sharing to a wider community.. Thus, as follow up to 2012 Learning Network Conference, we proposed to help MSP teams publish articles focused on mathematics teaching and learning accessible to a community broader than other MSP projects. Dr. Bharath Sriraman, editor of The Mathematics Enthusiast, generously offered us the opportunity to publish this special issue.We approach the task of guest editors as empathetic solicitors and reviewers of scholarship associated with MSP projects. We are leaders, ourselves, for multiple MSP projects, and have been since 2004, first for a middle school mathematics project (Math in the Middle Institute Partnership, http://scimath.unl.edu/MIM/) and now for a K-12 mathematics project [NebraskaMATH, http://scimath.unl.edu/nebraskamath/index.php): Smith is also a leader on a Research, Evaluation, and Technical Assistance (RETA) project [Data Connections, http://scimath.unl.edu/dataconnections/index.php). We understand the time-consuming nature and inherent challenges of trying to create meaningful professional development with teams of interdisciplinary IHE faculty, and partner with school districts, to offer professional development and study its impact on teachers and their students in the dynamic life of real districts, schools, and classrooms. We have experienced the learning of teachers and their students to be neither linear nor quick, therefore, we understand that studying STEM teaching and learning is messy, long term, and anything but straightforward. We understand that, for the most part, it is the same MSP leaders who are offering professional development as who are trying to study its effectiveness and that frequently the days are not long enough to do both simultaneously. Thus, we find MSP projects with their own rhythm and life, waxing and waning their research efforts in concert with their professional development offerings, with one or the other receiving more attention at any given point in time. All MSP project leaders must balance a set of teaching and research priorities in ways that never quite feel satisfactory. These are priorities and tensions that we, indeed, understand from the inside.We sent out a call for articles to the 2012 Learning Network Conference participants following the conference, and a motivated, hard working group of authors, who double as leaders for mathematics focused MSP projects, responded, some of whom are publishing their scholarship for the first time in this special issue. They have taken their 2012 conference presentation proposals and presentations focused on the theme of effective STEM teaching and created manuscripts. …