Reports of online writing courses at universities provide isolated experiences rather than multiple-case comparisons. This study uses activity theory to explore the nature of successful developments of four online writing courses in higher education. Universities desire online learning to meet strategic and accessibility needs. Faculty may lack skills and resources but administrators can provide supportive environments. Online learning risks higher dropouts and simplistic pedagogies, but effective design encourages productive interactions and ongoing course improvements. Six reported cases described online writing courses that either preserved classroom writing pedagogies, or addressed systemic dysfunctions in classroom courses. This qualitative study uses a convenience sample of four case studies recruited from online university courses in technical or professional writing in the United States and Canada. Information was collected through interviews with instructors and available personnel, course walkthroughs and artifacts. Cases were analyzed using activity theory. Cases consisted of undergraduate and graduate courses in technical or educational writing, legislative drafting, and proposal writing. The courses were ongoing activity systems constrained by professor experience and source materials, but subject to structural tensions that resulted in expanded motivations for access, achievability, and community integration. Stakeholders can recognize the impact on design from the reason the course was requested, professor independence, existing course materials, and ongoing measurement. The small sample was suitable for generating theory but not statistical generalization. Future research can explore courses in other countries and languages, writing disciplines, and institutions.