A simple method for investigating the relation between intrinsic viscosity and molecular weights of vinyl polymers is described. Unbranched polystyrene is found to obey Houwink's law with an exponent of 0$\cdot $65. Equations are given for calculating the number average degree of polymerization and molecular weight distribution in unfractionated polymers. It is pointed out that a method is now available for the preparation of polymers with known molecular weights and distribution. The absolute value of the velocity constant for the transfer reaction between styrene and carbon tetrachloride at 60 degrees C is calculated.