Adaptive teaching expertise is a critical component of quality teaching. University-based supervisors should employ specific supervision styles and discourse types during post-lesson observation conferences to help student teachers develop adaptive competencies such as, justifying decision-making, balancing experimentation and risk to pupils, and discussing instructional adaptations to address pupils' contextualized-needs. Findings from a sixteen-week, multiple-case study suggest that student teachers and supervisors (N = 6) do not use critical discourse to capitalize on opportunities to develop adaptive teaching expertise. If student teachers are expected to become adaptive experts, teacher educators must learn how to leverage discourse to promote development of adaptive teaching expertise. (Contains 11 tables.)