This paper reports the results of a content-analysis for the treatment of gender and diversity in the 11 top-selling lifespan developmental textbooks. The purposes were to measure the amount of information provided on aspects of development specific to Caucasian females and females of Color and to evaluate qualitatively the incorporation of the new research and theory on gender through experts' review of sections on gender role development. Results indicated that the amount of information provided on events in girls and women uniquely encounter throughout the lifespan, such as menstruation, pregnancy, rape, etc., was minimal in all 11 textbooks. Experts' qualitative ratings of the texts' section on gender role development for their race and gender bias were also disappointingly poor. Further, the texts contained almost no material on women (or men) of Color. Unlike most previous analyses of texts, this research focused on error of omission, since the absence of information is difficult to detect and yet may be potentially more damaging. The findings suggest that lifespan texts are deficient in their treatment of gender and diversity. A secondary finding was that the more efficient qualitative assessment yielded essentially the same results as the quantitative procedure. (Author)