The collaborative design of technology-enhanced learning is seen as a practical and effective professional development strategy, especially because teachers learn from each other as they share and apply knowledge. But how teacher design team participants draw on and develop their knowledge has not yet been investigated. This qualitative investigation explored the nature and content of teacher conversations while designing technology-enhanced learning for early literacy. To do so, four sub-studies were undertaken, each focusing on different aspects of design talk within six teams of teachers. Findings indicate that non-supported design team engagement is unlikely to yield professional development; basic process support can enable in-depth conversations; subject matter support is used and affects design-decisions; visualization of classroom enactment triggers the use of teachers' existing integrated technological pedagogical content knowledge; and individual teacher contributions vary in type. Implications for teacher design team members and facilitators are discussed.