The paper focuses on the infinitival clauses in Meadow Mari (Uralic; head-final, SOV) that allow overt subjects and/or agreement on the infinitive. We outline a novel analysis whereby embedded subjects in Mari are exceptionally licensed by a silent PDAT heading the infinitival clause and AGR becomes available due to the unique properties of the dative case, which in Mari was originally an adposition. We further put the data into a broader context by discussing the well-known analyses that postulate that the non-finite T has special Case/Agr properties (as proposed for Russian, a contact language, and Hungarian, another Uralic language) and showing that, although these approaches appear to match the data, they fail to make valid predictions. Thus, the Mari data contribute to the discussion of exceptional case marking across the world’s languages and highlight the diversity of constructions involving inflected infinitives and embedded dative subjects.