Certain modal auxiliary and control constructions in Thai differ only in the choice between a modal or control verb. Despite a possibility to analyze them as (subject) raising vs. control predicates, the present study argues that their counterparts with the marker thîi may not be derived via the raising vs. control conventions. The reasons include the presence of thîi cà{glottal stop} which marks infinitival complements and a possible connection between modal auxiliaries and lexical control verbs revealed by a test on Thai clausal idioms. This study proposes an additional functional category, Mood (Irrealis) Phrase, M(I)P, to account for the co-occurrence restrictions of thîi and non-assertive (irrealis) infinitival complements, and develops a unified analysis for modal and control constructions with thîi, parallel to Kayne's (2000) approach to control infinitives with di in Italian. The analysis developed here is consequential to the syntax and semantics of modals and control infinitives, cross-linguistically. Firstly, it suggests that modals that behave identically to control predicates be analyzed by means of the control approach, rather than the raising predicate approach, which has been held customarily. Secondly, it establishes the role of the MIP, which enables the expression of a hypothetical tense that occurs in infinitival complements introduced by markers (i.e. thîi in Thai, di in Italian, and de in French). © 2009 Elsevier B.V. All rights reserved.