The effects of polyamide molecular weight on morphology generation in nylon 6 blends with maleated elastomers are described. The elastomers used include styrene-butadiene-styrene block copolymers with a hydrogenated mid-block, SEES, and versions with X% grafted maleic anhydride, SEBS-g-MA-X%, and an ethylene/propylene copolymer, EPR, and a maleated version EPR-g-MA. The molecular weight of the nylon 6 phase governs the melt viscosity of the blend matrix and the number of amine end groups available for reaction with the maleic anhydride groups in the rubber phase; both of which influence the size, shape, and size distribution of the rubber phase formed during blending. In general, rubber particle size, distribution, and the amount of occluded material in the rubber phase decreases as the nylon 6 molecular weight increases. Measurement of the extent of reaction between the amine end groups and the grafted maleic anhydride revealed that a higher fraction of nylon 6 chains are grafted to the rubber matrix as the nylon 6 molecular weight increases. The weight average rubber particle size and size distribution for blends based on SEBS-g-MA-X% are smaller than corresponding blends based on SEBS/SEBS-g-MA-2% mixtures containing the same amount of maleic anhydride. EPR/EPR-g-MA mixtures produce nonspherical morphologies that are typically larger and more polydisperse than SEES type elastomers. One reason for this difference is the fact that SEES elastomers react more readily with nylon 6 than do EPR/ EPR-B-MA mixtures as determined by extent of amine reaction and torque rheometry. The weight average rubber particle size for blends of the various rubbers and nylon 6 materials were correlated using a modified Taylor theory analysis. A master curve was generated by determining shift factors needed to superimpose the maleated rubber/nylon 6 curves onto a reference curve for the non-maleated rubber, SEES. The overall shift factors correlate linearly with the maleic anhydride content of the rubber phase.