More than one in 20 female cancers in Europe are of the endometrium. Surveillance of incidence rates is imperative given the rapidly changing profile in the prevalence and distribution of the underlying determinants. This study presents an analysis of observed and age-period-cohort-modeled trends in 13 European countries. There were increasing trends among postmenopausal women in many Northern and Western countries. Denmark and possibly France and Switzerland were exceptions, with decreasing trends in postmenopausal women. In premenopausal and perimenopausal women, declines were observed in Northern and Western Europe, most evidently in Denmark, Sweden, and the United Kingdom, affecting consecutive generations born after 1925. These contrast with the increasing trends regardless of menopausal age in some Southern and Eastern European countries, particularly Slovakia and Slovenia. These observations provide evidence of changes in several established risk factors over time and have implications for possible primary prevention strategies. In postmenopausal women, changes in reproductive behavior and prevalence of overweight and obesity may partially account for the observed increases, as well as hormone replacement therapy use in certain countries. Combined oral contraceptive use may be responsible for the declines observed among women aged <55 years. Whereas there are some prospects for chemoprevention in premenopausal women as oral contraceptive use becomes more widespread in Europe, increases in obesity and decreases in fertility imply that endometrial cancer in postmenopausal women will become a more substantial public health problem in the future.