Karen J. Campbell's teaching repertoire and scholarly interests spanned centuries of German and Northern European literature and culture. In addition to beginning and intermediate German language courses, Professor Campbell taught medieval and modern German cultural surveys, as well as courses on the Germanic heroic epic, the Arthurian tradition, German and Danish fairy tales, and fin de siècle German literature. Beginning in 2013, Professor Campbell taught the first iterations of a new senior capstone seminar in German, a course focused on masterworks of the German literary tradition and the crafting of a research paper on a literary topic. Professor Campbell helped to establish the Foundations program through her perennially popular course, Narrative and Group Identity: The Case of the Vikings, which she later offered as a Connections II course. The geographic reach of the Vikings course extended from Scandinavia to Iceland and even Newfoundland, and Campbell brought insights from her own travels to the course material.

Professor Campbell's students admired the range and depth of her literary and cultural knowledge, as well as her insight and her wit. Students found her to be a caring instructor, wanting them to do well, as evidenced by the careful feedback she gave on student writing. Students frequently expressed their appreciation for the wealth of visual material Professor Campbell introduced in her classes, including local Pennsylvania German culture. These images opened students to new vistas on European cultural traditions and German-American culture. Campbell is an avid bibliophile, and her donations of books and other items enriched the Joseph International Center, the Klehr Center for Jewish Life, and the Shadek-Fackenthal Library.

During her 28 years at Franklin & Marshall, Professor Campbell served the College in numerous capacities. She founded the Keiper Forum, a venue for F&M faculty in the modern languages to share their research with one another, a tradition that was revived in recent years after a period of dormancy. Professor Campbell served as Chair of the Department of German and Russian and on the Budget Priorities Committee. She was instrumental in founding the program in Comparative Literary Studies and frequently offered courses within the program.

Professor Campbell's research interests and scholarly expertise were remarkably broad, ranging from German mysticism and the medieval epic to 19th-century Romanticism and Realism and early 20th-century classic texts. Along with an edited volume of German mystical writings, Professor Campbell's publications addressed the writing of 19th-century Austrian author Adalbert Stifter, as well as works by Franz Kafka and Rainer Maria Rilke. Her scholarly writing is remarkable for the depth and elegance with which she treats weighty topics.