The temporal categories of tense and aspect have received much attention in linguistic literature. But often scholars concentrate on their grammatical description without regard to their function in discourse. This work is a comprehensive and systematic description of the function of tense and aspect in the Obolo language. The data for this study are ten texts, both written and oral, from the Ngo dialect of Obolo, which is spoken in southeastern coastal Nigeria. They represent the four main discourse genres of narrative, procedural, expository, and hortatory. In the model adopted for this work, the discussion of tense and aspect in the sentence correlates with the referential component, while the discussion of the discourse functions of tense and aspect correlates with the textual component.