We sought to identify factors that discriminate between women with a lower genital tract infection and women with a lower genital tract infection and endometritis. This study enrolled women at risk for or having a lower genital tract infection with Chlamydia trachomatis or Neisseria gonorrhoeae and measured behavioral and clinical factors. Women were identified through contact tracing of male partners, presentation with cervicitis, or presentation with symptoms of pelvic inflammatory disease and classified as (1) having a lower genital tract infection without endometritis, (2) having a lower genital tract infection with endometritis, (3) having no lower genital tract infection with endometritis, and (4) having neither a lower genital tract infection nor endometritis. The primary comparison was between women having a lower genital tract infection without endometritis to women having a lower genital tract infection and endometritis. Women with a lower genital tract infection and endometritis were older and reported a history of more sexually transmitted diseases (70.0% vs. 56.7%), abdominal pain (82.2% vs. 60.0%), and use of barrier methods of contraception (28.9% vs. 8.6%) than women with a lower genital tract infection alone. The regression model found that women with a lower genital tract infection and endometritis were 7.1 times (95% CI = 2.2-23.0) more likely to report abdominal pain and 4.6 times (95% CI = 1.5-14.9) more likely to use barrier methods of contraception than women with a lower genital tract infection alone. These results suggest that behavioral factors, in addition to symptoms, can be used to identify women with and without upper genital tract involvement.