Economists stress the role of differences in relative prices (or costs) in explaining observed behavior. However, the full potential of this type of analysis for clarifying a number of fundamental socio-political issues involving "collective" (or "public") goods has not yet been fully realized. With scattered but notable exceptions,1 writers in the area have focused on what "should be," neglecting the question of more traditional scientific interest of what "will be." We propose to provide a step towards the development of a complete comparative statics of collective goods at the same time we begin to explore some of its implications. To start with, the notion of a collective good is placed in the context of some recent advances in consumer theory. Part I then examines the factors causing differences in the costs of private, relative to collective, goods and, hence, in the proportion of any desire gratified by each type of good. Some demand side factors are also analyzed. Part II explores the role of differences in relative costs in determining the selection of a collective decision making mechanism: central planning or the market. The latter choice can be regarded as a special case of choice among alternative collective modes of gratifying desires, which is the second half of a complete comparative statics of collective goods.