This dissertation presents the clarinet pedagogy of Robert Marcellus through reorganizing, documenting, and consolidating the archival recordings of summer master classes held at Northwestern University from 1977-1990. Pedagogical discussions and exercises are examined on topics such as wind, articulation, hand and finger position, and phrasing. Marcellus' interpretation and comments are discussed, along with musical examples from Cyrille Rose's 40 Studies for Clarinet, numbers 13, 21 and 32. This dissertation contains Marcellus' repertoire list and a sequence of study. Through this examination and consolidation of Marcellus' own words, this dissertation serves as a unique resource for those clarinetists interested in learning about this distinguished pedagogue.