Rectal prolapse frequently occurs in conjunction with functional and anatomic abnormalities of the bowel and pelvic floor. Prolapse surgery should have as its goal not only to correct the prolapse, but also to improve function to the greatest extent possible. Careful history-taking and physical exam continue to be the surgeon's best tools to put rectal prolapse in its functional context. Physiologic testing augments this and informs surgical decision-making. Defecography can identify concomitant middle compartment prolapse and pelvic floor hernias, potentially targeting patients for urogynecologic consultation or combined repair. Other tests, including manometry, ultrasound, and electrophysiologic testing, may be of utility in select cases. Here, we provide an overview of available testing options and their individual utility in rectal prolapse.