This paper is concerned with morphological derivation in Old English, specifically nominal and verbal derivation without affixation. Non-affixational derivation, which is traditionally called conversion, has been controversial in Old English word-formation. Morphologists` claims differ in the issues of the directionality of derivation and the postulation of a zero-morpheme. For example, Kastovsky (1968, 1992, 1996) argues for zero-derivation, postulating a zero-morpheme in Old English morphology while Dalton- Puffer (1992, 1993), Ritt (1993) and Lass (1993) give evidence against the assumption of zero-derivation in favor of affixless derivation (cf. Plag 2003). Concerning the directionality of affixless derivation, any principles or criteria for determining the directionality has not been offered in Old English morphology. Aiming to give alternative solutions to these two morphological problems, this article provides a morphological analysis of Old English ge-words. It is shown that the derivation of various derivative forms is accounted for by the interplay of Word- Class Marking and the Zero-Constraint without having the directionality problem. Furthermore, the non-occurrence of some derivatives is explained straightforwardly.