The crystallization behavior of Nylon-6 and the interaction in Nylon-6/nanoclay/functionalized polyolefin blends were investigated by X-ray diffraction and Fourier transform infrared spectroscopy. For samples without any thermal history, the interaction between Nylon-6 and nanoclay or the interaction between Nylon-6 and functionalized polyolefin favors the formation of gamma form crystal. In contrast, the presence of both nanoclay and functionalized polyolefin together in Nylon-6 was found to have an antagonistic effect on each other's ability to promote the formation of form crystal. This was attributed to the complex interactions between the constituents. The crystallization behavior of Nylon-6 in Nylon-6/nanoclay/functionalized polyolefin blends is clearly affected by the cointeraction of these effects. (C) 2007 Wiley Periodicals, Inc.