Teachers continuously engage in the relational work of sensemaking with students, but they generally do so isolated from colleagues, making individual decisions about their classrooms. Professional learning communities (PLCs), provide opportunities for collaborative professional reflection and development among peers centered on the analysis of teaching practice. However, PLCs can be difficult to implement in ways that reflect theories of adult learning and are manageable in light of the responsibilities of a teacher. We conducted a year-long case study of a PLC that engaged a group of middle school science teachers using artifacts from a digital portfolio and a framework for high-quality science teaching to explore their teaching practice. The PLC was divided into sessions facilitated externally by a member of the research team and sessions facilitated internally by the teachers themselves. Videos of all PLC sessions and baseline and final interviews indicated that unlike some PLCs described in the literature, participants focused their conversation and interactions on the content of science teaching regardless of who facilitated the session. The discussion was mediated by the digital portfolio tool, its artifacts and an introduced analytical framework. However, externally facilitated sessions revealed far more analysis of practice, compared to extensive reporting on portfolio artifacts when facilitated internally. The findings suggest that digital portfolios, when combined with analytical frameworks of practice can be important tools for teacher reflection, but attention must be paid to PLC structures and norms that move teachers past 'show and tell' and toward more in-depth conversations about practice.