This paper investigates tough-predicates and whether four verbs (suck, bite, blow, and work) can function as this type of predicate. The theoretical analysis uses two syntactic and two semantic properties of prototypical tough-predicates to determine the status of the tough-verb candidates. Syntactically, tough-predicates select a to-infinitival complement and require a referential dependency between the matrix subject and the object gap in the complement clause. Semantically, the matrix subject must possess an inherent or permanent property and tough-predicates assign an “experiencer” role. From these four diagnostic properties, the analysis concludes that suck, bite, and blow are indeed tough-verbs, while the conclusions concerning work are less definitive. To complement the conclusions of the theoretical analysis, native speaker judgements were collected from 22 Canadian English speakers. The results show that for a majority of the consultants, suck, bite, and blow can function as tough-predicates. The behaviour of these verbs suggests that suck, bite, and blow (and possibly work) should be added to the small list of known tough-verbs.