In this paper an attempt has been made to explore the major causes of price level changes in West Pakistan during the past thirteen years and to determine their relative importance in explaining the price fluctuations. A supplementary object of the paper is to develop a predictive mechanism which may be used to forecast the response of price level to changes in the explanatory variables used in the regression model. There is vast literature on inflation theory  but not so much on quantitative evidence. Broadly, there are three groups of theories of inflation: the demand pull theories, which state that inflationary pressures result from aggregate demand exceeding aggregate supply at full employment; the cost-push theories, which stress the producers’ power to pass on cost increases in higher prices even when demand remains unchanged. The third group of theories, which take a mid-way position between the demand-pull and the cost-push theories, are a number of structural theories, notably those associated with the names of Ackley, Eckstein, and Schultze [1,5,11]. According to Ackley, inflation results from mark-up of prices. He considers the price policies of the firms and the wage policies of the labour unions to be responsible for inflation. He puts forward the hypothesis that mark ups used by business in setting prices and those applied by the labour unions to their cost of living for getting higher wages tend to rise in an inflationary situation which results in pyramiding of costs. Professor Otto Eckstein advances the hypothesis that inflation may be caused by price increases in certain bottleneck industries even when there is no over-all excess demand in the economy.