Polyvinyl butyrals(PVBs) of systematically varying vinyl alcohol content have been synthesized and characterizing using wet chemistry, IR, DSC and TGA. The miscibility of polyvinyl butyral(PVB)/polymethyl methacrylate(PMMA) blends was studied by DSC, DMTA and SEM as a function of PMMA and vinyl alcohol(VA) content differences between the respective blend components. It is found that a blend of PVB containing 23 wt% VA with PMMA at a weight ratio of 80:20, repectively, was thermodynamically miscible. The miscibility parameter(MP) model used to estimate potential areas of compatibility/miscibility is based on the use of solubility parameters and the estimated region of compatibility/miscibility agrees with the experimental results.