The question, “Why use a mathematical programming model at the sectoral level?” is addressed. To address this question, discussion is presented mathematically and verbally upon mathematical programming sector models in which both price and quantity are endogenous variables. The discussion covers both the theoretical properties and the empirical concerns which must be faced in applying such models. Discussion is also presented upon the usefulness of the modeling approach for policy analysis. Selected bibliograpic citations' use of the approach in policy analysis are given.