Scholars have long debated whether Old and Middle English (ME) are different diachronic stages of one language, or whether they are two closely related languages that have different historical roots. A general assumption is that Middle and Modern English descend from Old English (OE), similar to the way Middle and Modern German descend from Old High German. Traditional scholarship places English into the West-Germanic language subgroup (which includes Old English, and continental Germanic languages) Historically, criteria used by linguists to establish genealogy of languages involve sound change from parent to daughter languages and the sharing of core vocabulary. Until recently, consideration of the influence of contact-induced change, except in the lexical domain, has been minimized, favoring generative language-internal factors. While it is generally accepted that internal motivation shapes the outcome of language change, contact may provide the catalyst for the change. The syntax of ME emerged with linguistic variation that distanced it from its Germanic relatives. In order to understand how the grammar of ME evolved and differs from its West-Germanic cousins, the syntax and morphosyntactic properties of ME, evident in The Orrmulum, an early ME work written in the Danelaw region of England, are analyzed in comparison to Old English (OE), Old Norse (ON), and Celtic, and in relation to formal grammaticalization theory, social factors and historical events. An analysis of the grammar in The Orrmulum supports current research regarding Scandinavian influence on the syntax of OE and ME, because there is extensive historic evidence regarding effects of language tangency of the relevant cultures; the properties of a grammatical lexicon influence retention of syntactic patterns, despite additions/changes in lexical categories; and The Orrmulum is a revealing source of the transition of OE to ME regional dialect variations.