Sexually active persons who self-select for syphilis testing  n=840 participants; ~280 per study site  Inclusion criteria:  - sexually active persons 18-64 years old  Exclusion criteria:  persons <18 years old; persons >64 years old; persons with limited or no reading skills; persons who previously participated in a NOWDx study  Expectant mothers  n=222 participants; ~74 per study site  Inclusion criteria:  - expectant mothers ≥18 years old  Exclusion criteria:  persons <18 years old; persons with limited or no reading skills; persons who previously participated in a NOWDx study  Lay users  n=48 participants; ~16 per study site  Inclusion criteria:  persons 18-64 years old; -½ high risk sexual behavior; ½ low risk sexual behavior  Exclusion criteria:  persons <18 years old; persons >64 years old; persons with limited or no reading skills; persons who previously participated in a NOWDx study