This article critically assesses Lightfoot's (1991, 2006) ‘degree-0 theory’ of language change, specifically the use that Lightfoot makes of empirical data from Old English (OE) and Middle English (ME). This is followed by the presentation of a recent analysis of word order in a variety of OE and ME sources. It is argued that data from these periods do not support the ‘degree-0 theory’. Rather, the data demonstrate that verb-final and object–verb order were less dominant in OE subordinate clauses than previously assumed, and that the shift to SV order was fairly gradual. There is also little in the data to suggest that subordinate clauses and main clauses developed in radically different manners or at radically different speeds. The article highlights the importance of careful data usage, both with respect to type and scope of material, and the interpretation of data collected and categorised by others.