Educational Psychology Series: Evaluating the Quality of Learning: The SOLO Taxonomy (Structure of the Observed Learning Outcome) focuses on the approaches, methodologies, and techniques employed in the valuation of the quality of learning. The publication first offers information on the quality and quantity of learning and origin and description of the Structure of the Observed Learning Outcome (SOLO) taxonomy. Discussions focus on general intellectual development and the growth of quality; some assumptions and applications of stage theory; from developmental stage to levels of learning quality; and general intellectual development and the growth of quality. The text then examines the teaching of history, elementary mathematics, English, and geography. Topics include interpreting a map and drawing conclusions, explaining a natural phenomenon, appreciation of poetry, implications for the teaching of history, English, and mathematics, numbers and operations, and general application of SOLO to history. The manuscript takes a look at modern languages, place of the taxonomy in instructional design, and some methodological considerations. Concerns include alternative formats for obtaining SOLO responses, instructional processes, curriculum analysis, remediation, and teacher intentions. The publication is a vital source of data for educators interested in the SOLO taxonomy.