An essential point to arise out of macroeconomic literature of the last twenty years is that imperfect competition in product markets allows scope for aggregate demand to affect the level of output and employment; and to have positive impacts on “welfare”. The present paper considers the connection between “imperfect competition” and macroeconomic outcomes from a Sraffian perspective. In this case, the appropriate categorisation is one of restricted versus unrestricted competition: essentially the ability of intersectoral capital mobility to enforce a uniform rate of profit. The paper also considers the significance of product differentiation, which is generally assumed to be the defining characteristic of imperfectly competitive markets. A Sraffian approach makes clear the limited significance of the concept product differentiation in a multi-commodity framework particularly in drawing hard and fast implications about “welfare”. The investigation of connections between restricted competition and macro outcomes therefore turns largely on the significance of restrictions on mobility for output and employment multipliers.