Development of the Assessment in Spondyloarthritis International Society (ASAS) classification criteria for axial spondyloarthritis (SpA) was one of the major breakthroughs in the field over the past decade. Despite some concerns related to the specificity of the criteria, they stimulated research into the early stage of the disease. This resulted in major advances in the understanding of the course of the disease, revealing predictors of progression, improvement in early diagnosis and treatment in axial SpA. In this review, we summarize the recent developments resulting from the introduction of the ASAS classification criteria for axial SpA and the implications for research and clinical practice.