In this work, the properties of Poly(methyl methacrylate) (PMMA)-clay nanocomposites prepared by three different manufacturing techniques viz., solution mixing, melt mixing, and in-situ bulk polymerization in presence of clay were studied. Morphological analysis revealed that the extent of intercalation and dispersion of the nanoclay were relatively higher in the in-situ polymerized nanocomposites than those of solution and melt blended nanocomposites. Differential Scanning Calorimetric study indicated maximum increment in T-g of the PMMA in the in-situ polymerized PMMA-clay nanocomposites. Thermo gravimetric analysis showed improved thermal stability of PMMA in all the nanocomposites and the maximum improvement was for in-situ polymerized nanocomposites. The storage moduli of all the nanocomposites were higher than the pure PMMA. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3012-3018, 2009