Objective.To develop a whole-body magnetic resonance imaging (MRI) scoring system for peripheral arthritis and enthesitis.Methods.After consensus on definitions/locations of MRI pathologies, 4 multireader exercises were performed. Eighty-three joints were scored 0–3 separately for synovitis and osteitis, and 33 entheses 0–3 separately for soft tissue inflammation and osteitis.Results.In the last exercise, reliability was moderate-good for musculoskeletal radiologists and rheumatologists with previously demonstrated good scoring proficiency. Median pairwise single-measure/average-measure ICC were 0.67/0.80 for status scores and 0.69/0.82 for change scores; κ ranged 0.35–0.77.Conclusion.Whole-body MRI scoring of peripheral arthritis and enthesitis is reliable, which encourages further testing and refinement in clinical trials.