Experimental investigations show that fluidized binary mixtures exhibit varied pressure drop profiles and segregation patterns, depending on the level of disparity due to size and/or density differences. In this study, different mixture types are mapped on a graph of density versus size ratios. It is found that the ratio of the minimum fluidization velocities of individual components can be used to categorize these mixtures. A simple correlation is developed to compute the ratio of the minimum fluidization velocities based on the density and size ratios. Categorizing the binary mixtures in this manner gives a qualitative understanding of how the different mixtures behave on fluidization. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 1446-1458, 2011