This study investigates truth commitment in spoken Modern Greek through constructions of the type λέω + ότι (‘say + that’). Drawing on a corpus-driven analysis of approximately 127,000 words of naturally occurring everyday conversations, the study examines the semantic and pragmatic properties of the construction and its interaction with grammatical categories such as tense, person, mood, polarity and modality. It is found that the prototypical function of λέω + ότι is the reporting of speech, thoughts or information from both spoken and written sources, while the construction also develops important discourse-organizing and evidential functions. Its interpretation is highly sensitive to contextual and interactional factors, allowing speakers to negotiate the truth value and factual status of the embedded proposition in real-time communication. Negative, interrogative and modal environments, as well as person and tense distinctions, systematically influence speakers’ epistemic commitment and the interpretation of the complement clause. The analysis suggests that truth commitment in spontaneous conversation is not a fixed semantic property, but a dynamic phenomenon shaped by discourse context and speaker interaction. More broadly, the study highlights the contribution of spoken corpora to semantic and pragmatic research and argues for the importance of authentic conversational data in theories of meaning and truth conditions.