Although an epistemic change often is labeled as a shift, some researchers representing the social sciences consider this paradigm shift as a paradigm expansion (e.g., Pollack, 2007) because epistemological and methodological diversity allows researchers to address a wider range of questions. The third paradigm, mixed methods (MM) research, is claimed to provide a more holistic picture of a research problem by combining two different data sourcesquantitative and qualitative-in a single study (Creswell & Plano Clark, 2007;Greene, 2007;Teddlie & Tashakkori, 2009). This article discusses how mixed methods research approaches have been used to enrich the results and to enhance the rigor of classroom-based language assessment investigations, drawing on both the language testing and assessment (hereafter, language assessment) and classroom assessment literature in second language education. The article opens with a brief overview of the methodological evolution in language assessment research. Then, focusing on MM research studies that investigated various facets of classroom-based language assessment (CBLA) practices, the main part of this article outlines a proposal of MM methodology as an appropriate methodology for research on CBLA, particularly in a context where a new form of assessment is implemented. The article closes with a discussion of challenges that MM researchers might face, and a proposal of MM research methodology as an appropriate research approach for CBLA scholars, especially in settings where both the validation of assessment and the explanation of the phenomenon are required.