Critiquing is the process of providing reasoned opinion on an object. it is essential as a supplementary problem solving activity in any co-operative problem solving environment to provide selective portions of knowledge to the u@ers In the form of why not kind of explanations. In this article, we discuss about CAFE - A knowledge based Critic for Architectural Floor-plan Evaluation. It provides textual-criticism by evaluating floor-plans of residential buildings with respect to different factors of function-utility, basic planning principles and client expectations. Floor-plan evaluation is a complex task that requires to model different components of knowledge there is a need to handle abstractions and the problem solving behavior required by the critic is quite; complex requiring a dynamic agenda based approach that allows identification of goals from the given situation. This forms the motivation for building a knowledge based system for It. We discuss in detail about this system CAFE, the underlying assumptions, types of critic rules handled, knowledge representation and the problem solving scheme followed. We also present a typical scenario with CAPE. Finally, we analyze the system and propose extensions. © 1991 IEEE.