The general topic of this paper is the morphological status of the causative formation by means of the Indo-European suffix *-éje-/-éjo- (henceforth ‘jan’-formation) in Old English and its relation to other areas of research in the history of the English language. The paper has two specific aims. On the one hand, the degree of lexicalization of this word-formation type will be assessed, as well as its consequences for determining the degree of productivity of stem alternations in Old English. On the other, a case will be made for the ‘jan’-formation as an early instance of morphological loss, possible implications of this insight for the following two issues will be proposed: 1) The dating of morphological loss in the history of English; 2) The fixation of word order of Middle English. To sustain the second claim, a pilot study on the syntax in constructions with labile verbs in Early Middle English will be presented.