The purpose of this study was to clarify the mechanism by which bladder training affects urinary incontinence. Urodynamic data and specific urodynamic diagnoses of 108 women with urinary incontinence were compared before and 6 months after treatment with bladder training. Before treatment, 76 women had sphincteric incompetence, 11 had detrusor instability, and 16 had both. After treatment, 33 women no longer fulfilled the urodynamic diagnostic criteria for either sphincter or detrusor dysfunction. Controlling for severity before treatment, the number of incontinent episodes post-treatment was not associated with change in urodynamic diagnosis. Only the first sensation to void, voided volume, compliance, functional urethral length, and flow time showed any significant changes between pre- and post-treatment evaluations; however, none were correlated with change in the number of incontinent episodes. Bladder training does not appear to affect lower tract urodynamic variables or specific urodynamic diagnosis, and it is likely that its mechanism of action reflects adaptive behavioral changes. Physiologic changes not detected with techniques and/or criteria used in this study may still occur.