In the evolution of morphological studies, morphological features and markedness have come to play increasingly important rôles. Feature notation in morphology allows the development of the notion of natural morphological class, renders explicit much of the internal structure of paradigms and permits the exploitation, suitably adapted, of many of the results obtained in phonology. Markedness considerations, particularly when linked to general theories of morphology, again highlight morphological structure, constrain the variety of permitted analyses, and indicate, at least in part, the expected direction of historical change. In the sections to follow, I will present an analysis of Old French nominal and adjectival inflection which makes key use of morphological features and the differences between the marked and unmarked values of these features. This study will be particularly concerned with constraining the morphological analysis of Old French and conversely, with using Old French data to investigate more general properties of morphological systems.