© 2014, Canadian Center of Science and Education. All rights reserved. This paper are investigated questions of interrelation of quality and demand and are considered concepts, which limiting utility, quality and demand On the basis of revealing of interconnection between theories of welfare and markets of imperfect competition, by quality non-homogeneity of goods and services, consumers and producers there determines the influence of public welfare on mechanisms of imperfect competition market and their adverse effect on public welfare which includes stimulation of demand and growth of welfare on the basis of rising level of quality of produced and consumed goods and services. In this article we tried to complete and expand the scientific ...