Two studies were conducted to revise and empirically test Ellis’s framework for inadequate and harmful supervision, and to determine the occurrence of inadequate and harmful clinical supervision from the supervisees’ perspective. For Study 1, we delineated 10 criteria for minimally adequate clinical supervision and defined inadequate and harmful supervision by differentiating self-identified and de facto supervision for each. Ratings from 34 supervision experts were used to generate a taxonomy of 16 de facto inadequate and 21 de facto harmful supervision descriptors. Because harmful supervision was distinct from yet subsumed by inadequate supervision: we revised the taxonomy and definitions accordingly. In Study 2, the occurrence of inadequate and harmful supervision was assessed for 363 supervisees; 93.0% were currently receiving inadequate supervision and 35.3% were currently receiving harmful supervision. Over half of the supervisees had received harmful clinical supervision at some point. Implications for research, training, and practice are discussed.