I. The problem: the effect of consumer attachments upon competitive equilibrium, 31. — Definitions and assumptions, 32. — II. The Chamberlinian theory as a limiting case, 34. — Buyer attachments, 36. — Asymmetry in the relation of a price increase to a price decrease, 39. — Modification of the homogeneity requirement, 42. — III. Cross elasticities, 42. — Extra-marginal buyers, 46. — IV. Equilibrium at minimum cost, 50. — V. Can product differentiation be maintained in the long run? 54. — VI. The definition of a "perfect market, " 59. — Free entry, 60. — VII. Results and implications, 61.