The influence of P – Delta effects on the response of buildings subjected to earthquake ground motion is illustrated using time – history studies. It is shown that the influence of P – Delta effects is of great importance for buildings responding in a highly inelastic manner. However, for buildings responding in an elastic or slightly inelastic manner, the influence of P – Delta effects is relatively small. The stability factor approach for estimating the influence of P – Delta effects is reviewed. It appears that this approach gives reasonable results only for systems responding in an elastic or slightly inelastic manner. The strength and drift characteristics of buildings are briefly described. The results presented suggest that the response of certain types of well-designed buildings will not be significantly influenced by P – Delta effects. Finally, recommendations are made for assessing the significance of P – Delta effects for a given building design.