This paper has two main aims. First. it attempts to test a Keynesian (Tobin's q) investment function for the Turkish private sector within a dynamic stochastic model framework between the years 1963-85. Second it sets out to compare its results with those of-a previous Neoclassical work of a similar track, and concludes that it is the phenomenon of the composition of pubfic capita) rather than Its method of finance which explains private capital accumulation in the Turkish context.