English-ing-clauses as in (1) are non-finite clauses built around a verbal head in-ing. Although they all look suspiciously alike, some grammarians argue that-ing-clauses divide into gerunds and present participles (e.g. Jespersen 1940; Declerck 1991). (1) a. He was ruthless, and as to being a villainhe probably was. (1993, BNC) b. Ruth bit her lip and stared at him, not knowing what to say or do. (1993, BNC) c. Until he told her what it was she couldn't even deny having it. (1992, BNC) d. And even if she had cried out, who takes any notice of anyone shouting, even screaming? (1988, BNC) The crucial difference is that gerunds are nominalizations, while present participles are not. This means that gerunds, unlike present participles, occur in the positions typically reserved for noun phrases. Being a villain in (1a) occupies the slot following a preposition, while having it in (1c) functions as direct object to a verb. Therefore, both are gerunds. In contrast, present participles occupy adjectival or adverbial positions. So, because not knowing what to say or do in (1b) functions as an adverbial clause, and shouting in (1d) functions as a restrictive relative clause to anyone, both are present participles. The distinction between gerunds and participles is not generally accepted, at least not for Present-Day English. In the reference grammars by Quirk et al. (1985) and Biber et al. (1999) the distinction is simply not applied. In Huddleston & Pullum (2002) it is explicitly taken issue with, gerunds and present participles being replaced by a single category of "gerund participials". Regardless of whether the distinction makes synchronic sense, however, it has an uncontested basis in historical fact, as gerunds and present participles derive from historically distinct sources. Indeed, the divided opinions between reference grammars can be thought of as reflecting a situation of syntactic ambivalence that is simply the most recent stage in a gradual but incomplete syntactic merger (De Smet 2010). The goal of this chapter is to outline the bigger picture of categorial collapse in the English system of gerunds and present participles and then to link it to the situation found in Late Modern English. As is to be shown, morphosyntactic changes that involve confusion between gerunds and present participles were few and isolated during the Late Modern period. Their very occurrence naturally testifies to a blurring of the lines between the two clause typesand of course the changes further contributed to the blurring. But the evident constraints on their occurrence show that the gerund/participle distinction was certainly not completely defunct in Late Modern English. In what follows, Section 2 discusses the overall history of gerunds and present participles in more detail. Against that background, Section 3 presents a number of changes in Late Modern English. The focus is on complement constructions involving gerunds and present participles as this domain seems to particularly lend itself to confusion between the two claus...