(cross-leveled with ECONOM 7351). Theory of rational behavior in consumption, production, and pricing decisions of households and firms. Partial equilibria in product and factor markets under competition, monopoly, oligopoly, and monopolistic competition. A brief introduction to general equilibrium and welfare economics is provided. Calculus is employed. Students who have already completed ECONOM 4351 are not eligible to earn credit for ECONOM 3251. Prerequisites: (ECONOM 1014 or ABM 1041 or ECONOM 1000 or ECONOM 1051H) and (MATH 1400 or MATH 1500) or equivalent.