PURPOSE To provide evidence-based recommendations on the treatment of multiple myeloma to practicing physicians and others. METHODS ASCO and Cancer Care Ontario convened an Expert Panel of medical oncology, surgery, radiation oncology, and advocacy experts to conduct a literature search, which included systematic reviews,meta-analyses, randomized controlled trials, and some phase II studies published from 2005 through 2018. Outcomes of interest included survival, progression-free survival, response rate, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations. RESULTS The literature search identified 124 relevant studies to inform the evidence base for this guideline. RECOMMENDATIONS Evidence-based recommendations were developed for patients with multiple myeloma who are transplantation eligible and those who are ineligible and for patients with relapsed or refractory disease. Additional information is available at www.asco.org/hematologic-malignancies-guidelines.