Teacher professional development (PD) is considered essential to improving student achievement toward high standards. I argue that while current notions of high quality PD foreground cognitive aspects of learning, they undertheorize the influence of relational dynamics in teacher learning interactions. That is, current conceptions of high quality PD may be necessary but insufficient to engender teacher learning, and attention to relational dynamics may be essential to leveraging teachers' engagement and productive participation in learning opportunities. A review of the literature from related fields provides preliminary recommendations for addressing affective concerns and relational dynamics in learning, but extrapolation of these recommendations for PD is problematized by particular considerations of teachers as learners, including bureaucratic presses and hierarchical school contexts. A conceptual framework that incorporates power/knowledge considerations may allow for investigation of relational dynamics in PD interactions in a way that takes into account the participants' individual characteristics as well as institutional context. This study uses discourse analysis to examine interactions between three focal teachers and their PD facilitators in a science learning progressions project and a literacy coaching cycle. Examining moments of tension or questions raised by the focal teachers, my analysis finds that close attention to both verbal and nonverbal discourse moves in PD interactions illuminates the ways in which relational dynamics were consequential to the teachers' participation and can help explain the progress or lack of progress for each teacher.