Summary statement: In the absence of theoretical or empirical agreement on how to establish and maintain engagement in instructor-led health care simulation debriefings, we organize a set of promising practices we have identified in closely related fields and our own work. We argue that certain practices create a psychologically safe context for learning, a so-called safe container. Establishing a safe container, in turn, allows learners to engage actively in simulation plus debriefings despite possible disruptions to that engagement such as unrealistic aspects of the simulation, potential threats to their professional identity, or frank discussion of mistakes. Establishing a psychologically safe context includes the practices of (1) clarifying expectations, (2) establishing a "fiction contract" with participants, (3) attending to logistic details, and (4) declaring and enacting a commitment to respecting learners and concern for their psychological safety. As instructors collaborate with learners to perform these practices, consistency between what instructors say and do may also impact learners' engagement.