Rumination syndrome (RS) is characterized by the repeated regurgitation of material during or soon after eating with the subsequent rechewing, reswallowing, or spitting out of the regurgitated material. Rumination syndrome is classified as both a "Functional Gastroduodenal Disorder" (by the Rome Foundation's Functional Gastrointestinal Disorders: Disorders of Gut-Brain Interaction, 4th edition) and a "Feeding and Eating Disorder" (by the Diagnostic and Statistical Manual of Mental Disorders, 5th edition). Rumination syndrome is a disorder that is often inaccurately diagnosed or missed, resulting in patients experiencing protracted symptoms and not receiving treatment for long periods. There is a lack of clear consensus for RS diagnosis, mechanisms that maintain RS, and treatment. Guided by existing research and our clinical expertise, we synthesize available evidence and provide recommendations for clinical use. We present a case example and critically summarize the literature to date to (i) increase clinicians' understanding of heterogeneous clinical presentations, (ii) suggest assessment strategies to facilitate accurate diagnosis, and (iii) provide a schematic for intervention options. Overall, we recommend clinicians recognize the heterogeneous features of RS when considering diagnosis, assess for RS symptoms by clinical history, and treat RS with targeted diaphragmatic breathing while using other methods as augmented intervention or alternative treatment.