Experiments were carried out extensively to study the effectiveness of promoters in reducing bed expansion in gas-solid fluidized beds with distributors of varying open areas. Four types of rod promoters, seven types of disk promoters along with one blade promoter were used in beds supported respectively on five distributors with open areas of 12.9, 8.96, 5.74, 3.23 and 1.43% of the column section. Four correlations for bed expansion ratio were developed respectively for the unpromoted and the promoted beds with rod, disk and blade type promoters. The values of bed expansion ratio obtained from the developed correlations agreed fairly well with the experimental values.