Seed P is predominantly bound in the organic compound phytate, which makes the bioavailability of P low for monogastric animals fed maize (Zea mays L.)-based diets. Decreasing phytate and increasing inorganic P (P_i, an available form of P) concentrations in maize grain would be desirable to help ameliorate environmental problems associated with high P in feces. Our objective was to investigate the potential of improving the P profile of maize grain through breeding and selection. Ninety S₁ families from the BS31 population were evaluated at two locations for phytate, P_i, and other grain quality and agronomic traits. Phytate concentrations ranged from 1.98 to 2.46 g kg⁻¹, and the broad-sense heritability (H) was relatively low (0.60). Both genetic variance and H (0.84) were much greater for P_i Few unfavorable genetic correlations were observed between either P_i or phytate and other key economic traits. Also, selection differentials of multiple trait indices indicated that the P profile of maize grain and grain yield and moisture could be improved simultaneously. Many cycles of selection will be needed, however, to reach desirable phytate and P_i concentrations, especially when selecting for multiple traits. Regardless, our results are encouraging given that the families evaluated were related S₁ families and the number of families was relatively small.