Attitude verbs, which typically describe mental states, like English think, want, and know, are found in languages around the world. These verbs pose a number of interesting puzzles. One long-standing puzzle is how children come to learn the meaning of these verbs, which describe highly abstract mental states and so cannot be easily learned by observation. An influential account explains this fact with syntactic bootstrapping: attitude verbs can be differentiated by their morphosyntax, and children can use easier-to-observe morphosyntactic distinctions to draw conclusions about harder-to-observe verb meanings. But to what extent do attitude verbs have distinctive syntactic properties? In fact, given cross-linguistic variation, [...]