Following Smith's (1991, 1997) two-component theory, this dissertation investigates the structural characteristics and the semantic properties of the temporal system, including tense, mood, viewpoint aspect, situation aspect and discourse modes, of Iquito, a highly endangered and moribund language spoken in the northern Peruvian Amazon. Iquito has three tenses: Extended Current Tense, Recent Past Tense, and Distant Past Tense. Extended Current Tense gives a Reference Time (RT) frame from the day which includes Speech Time (SpT) to the infinite future. Therefore, situations occurring earlier on the same day or unrealized situations both appear in sentences with this tense. The temporal interpretation is inferred from the combination of aspect and mood morphology. Recent Past Tense gives a frame of RT from yesterday to one to two years prior to SpT. Distant Past Tense gives a frame of RT from one to two years prior to SpT extending backward to the infinitely remote past. Temporal boundaries among the tenses are not rigidly fixed in terms of a metrical conception of time. Iquito has seven perfective aspects, including a General, a Momentary, a Remote, two Deictic, an Allative, and an Ablative Perfective Aspect and one Imperfective Aspect. Remote Perfective Aspect incorporates an adverbial component while Ablative and Allative Perfectives incorporate directional components and Deictic Perfectives incorporate deictic components. The system of perfective aspects in Iquito manifests the importance of expressing the realization of an event in conjunction with information about the time of the day, location, and routing in terms of location. Regarding situation aspect, I propose that there are six types in Iquito, including States, Activities, Accomplishments, Achievements, Semelfactives and Motions, which all manifest language-specific correlates. With respect to grammatical moods, realis and irrealis moods are manifested in Iquito through a typologically unique strategy: word order change and vowel hiatus resolution. Regarding Discourse Modes, I find four modes in Iquito, including Narrative, Report, Description and Information. In addition, Quoted Speech manifests an interesting mixture of modes. This dissertation adds another dimension to the close connections among tense, aspect and mood, and contributes to linguistic documentation and advances the structural and semantic analysis of Iquito and Amazonian languages. It also contributes to research on the crosslinguistic variation of temporal semantics and to linguistics in general through an interesting case study. / text