Class enrollment sizes for online learning in higher education, a topic of persistent interest in the academic literature, impact student learning, pedagogical strategies, school finances, and faculty workload. Yet in the research literature, class size is addressed with insufficient specificity to provide enrollment direction. Seeking guidelines for determining online class sizes, the authors conducted a qualitative research synthesis from 43 recent higher education journals, yielding 58 evidence-based articles. It is clear that no one size fits all. Findings reflect that large classes (= 40 students) are effective for foundational and factual knowledge acquisition requiring less individualized faculty-student interaction. Small classes (= 15 students) are indicated for courses intending to develop higher order thinking, mastery of complex knowledge, and student skill development. Pedagogical intent should dictate class size. Using well-established learning theories, the authors describe current understandings of online enrollments and propose an analytical framework for pedagogically driven, numerically specific class sizes. Highlights: (1) There is academic interest in online course sizes in higher education; (2) Research indicates "no one size fits all" online classes; (3) Class sizes should be based on learning level and identified pedagogical intent; (4) Large classes are appropriate for foundation-level learning; and (5) Small classes are appropriate for learning requiring higher order thinking.