||Assessed the construct validity of class ratings of instructors measured by the Course-Faculty Instrument. Two sets of variables were used that explicate aspects of the nomological network of instructor ratings: (a) Three intrinsic variables of instructor behavior represented sources of rating variance that are considered valid (e.g., perceived effectiveness of instructor communications). (b) Six extrinsic variables represented variance often considered to be undesirable (e.g., instructor sex). 89% of the variance in 10,738 students' ratings of 129 instructors teaching 334 classes was explained by the intrinsic measures of instructor behavior. Three of the extrinsic variables (experience, rank, and publishing activities) correlated significantly with intrinsic variables and/or ratings. However, these latter variables may be as suggestive of validity as of bias.