This entry provides a comprehensive overview of the fundamental issues related to art therapy, encompassing the terminology, characteristics of the approaches within which art therapy interventions are conducted, and the methodology of art therapy research. This entry is composed of three sections. First, definitional problems of art therapy are explained. Second, a taxonomy of art therapy practices. This section addresses the issue of the continuum of art therapy practice, ranging from practices focused on art, also known as art brut, to practices based on psychotherapy approaches. The author provides a characterization of the most well-known clinical approaches in art therapy based on the typology of Malchiodi and Rubin, with examples of artistic techniques used. These include psychodynamic art therapy, humanistic art therapy with its spiritual variants, cognitive and behavioral art therapy, solution-focused art therapy, and systemic and integrative approaches. This section also explores developmental approaches linked to the concept of neurosequential development and the Expressive Therapies Continuum. Third, difficulties associated with the field of art therapy research, including methodologies for solving problems arising from the intersection of quantitative and qualitative frameworks. This entry references the proposal by Kapitan for “the mapping art therapy knowledge claims” and “an inclusive framework” for research in this area. This entry also references the ideas of research problems in art therapy proposed by Deaver. In addition, the author presents her own proposal for mapping quantitative and qualitative research in art therapy. This proposal is complemented by examples of research representing selected solutions.