The objective of this study is to explore a) which dimension of student ratings and which aspects of perceived instruction are affected by the two organizational factors, enrollment size and academic affiliation, and b) the nature of their effect. Two thousand five hundred students participating in 125 courses evaluated their instructors on Q-I "Evaluation of Instruction by Students". The 125 evaluated instructors responded to Q-2 "Perception of own Instruction" indicating the extent to which they employ various teaching planning and strategy attributes (TPS). Major findings suggest that academic affiliation has no effect on student ratings yet affects abstract aspects of perceived instruction. Instructors of the social sciences, unlike those of the humanities, manifest a vocational outlook in their instruction planning. Data indicate that enrollment size has an effect on the dimensions of student ratings and the perceived instruction, referring to concrete aspects of teaching. Students participating in small classes are more critical of instruction than those in larger classes. The nature of its effect on perceived instruction is mainly in terms of practical solutions of teaching methods and strategies and is hardly manifested in the planning phase of instruction. The relevance of these findings to university administrators is also discussed.