We report a study that explored the mechanisms used in hypothesizing meanings for novel motion predicates (verbs and prepositions) cross-linguistically. Motion stimuli were presented to English- and Greek-speaking adults and preschoolers accompanied by (a) a novel intransitive verb, (b) a novel transitive verb, (c) a novel transitive preposition, or (d) no novel predicate. Our study provides evidence that both language-specific (lexical) and universal (syntactic and semantic-geometric) factors shape the acquisition of motion predicates cross-linguistically. Lexical biases lead to distinct interpretations (more or less manner- vs. path-oriented) for novel intransitive verbs in English and Greek; however, syntactic (transitivity) cues overcome lexical biases and lead to uniformly path interpretations for novel transitive verbs in both languages. Syntactic (transitivity) cues also lead to path interpretations of novel motion prepositions. Finally, semantic-geometric constraints lead learners in both languages to assume that path interpretations abstract away from visual details of the motion path.