American economist known for his theories on industrial monopolies and competition (monopoly and competition).

Chamberlin studied at the University of Iowa, where he was influenced by economist Frank H. Knight (Knight, Frank Hyneman). He pursued graduate work at the University of Michigan and in 1927 obtained his Ph.D. from Harvard University, where he stayed for the rest of his academic career. His doctoral thesis became the basis for Theory of Monopolistic Competition (1933), a book that spurred discussion of competition, especially between firms whose consumers have preferences for particular products and firms that control the prices of their products without being monopolists.

The solutions that Chamberlin proposed are similar to those put forth by British economist Joan Robinson (Robinson, Joan) at the University of Cambridge, whose book was published a few months after Chamberlin's. Chamberlin's work offers the deepest insight into the workings of an economy in which firms actively compete by advertising, seeking locational advantage, and differentiating their products. Indeed, Chamberlin is the economist who coined the term product differentiation.

One of the implications of Chamberlin's model is that firms in a monopolistically competitive industry will be “too small” relative to their size if they do not differentiate their products. Chamberlin himself, however, considered small size a necessity if consumers are to have the variety they desire.