Bacillus cereus is the bacterial base for a new biochemical with plant growth regulating activity. The objective of this study was to determine the effects of multiple, early-season foliar applications of five formulations of Bacillus cereus and mepiquat chloride on growth and yield of upland cotton. Inhibiting effects of mepiquat chloride on expansive growth were maintained or enhanced with the addition of Bacillus cereus. The number of fruiting positions (number of nodes in sympodial branches) was decreased by formulations having 3 and 4% of mepiquat chloride, but this effect appeared to be somewhat counteracted by the addition of 2 g/gallon of Bacillus cereus. Yield responses to the addition of Bacillus cereus to mepiquat chloride were mixed between the two locations and the two years, and overall did not show a consistent improvement of the effects mepiquat chloride on yield of cotton.