The discovery, over the last forty years or so, of specific myositis auto-antibodies (easily dosed in routine nowadays) and the fine clinically and pathologically phenotypic descriptions of affected patients have made it possible to review the classification of inflammatory myopathies. The arrival of “omic” techniques has also led to the discovery of different pathophysiological mechanisms among these different subgroups of myositis. Naturally, therapeutic approaches specifically targeting the representative abnormal pathways of each subgroup are being evaluated. This modern approach to myositis, which is clinical, pathophysiological, and therapeutic in the making, is presented in this review article.