This essay focuses on trust in the automation within macrocognitive work systems. The authors emphasize the dynamics of trust. They consider numerous different meanings or kinds of trust, and different modes of operation in which trust dynamics play a role. Their goal is to contribute to the development of a methodology for designing and analyzing collaborative human-centered work systems, a methodology that might promote both trust "calibration" and appropriate reliance. The analysis suggests an ontology for what the authors call "active exploration for trusting" (AET).