This study examines the prepositional phrase in Dholuo. It is anchored on the following three objectives: to describe the structure of the PP in Dholuo, to identify the syntactic functions of the PP in Dholuo and to explain the PP in Dholuo within the X-bar. The study employed the descriptive research design which is qualitative in nature because it determines and reports things the way they are. Sampling for this study was done in stages. First, the study employed stratified sampling to arrive at 37 secondary schools out of the 40 secondary schools in Rarieda Sub- county.  Random sampling was then conducted by giving the 37 schools random numbers before picking on Okela secondary school. The form three class was then purposively chosen to write a composition in Dholuo. The researcher also purposively sampled three books from the Dholuo Bible namely Luke 5, Acts 3 and Exodus 14. Introspection was also used when necessary. From these sources, sentences that contained PPs were extracted or generated, coded and described in terms of structure and function before being analyzed within the X-bar theory. Each structure and function were identified once to avoid duplication. Our study found out the following in terms of structure: that the PP in Dholuo exhibits the structures P+NP, P+AdvP and P+PP. The structure P and AdjP does not exist. It also emerged that where P is followed by an NP in the form of a pronoun, the pronoun is agglutinated within the P. Moreover, the structure P and AdvP depends on syntactic relations that determine the syntactic well formedness of the sentence. In terms of functions, the study revealed that PP in Dholuo can function as complement, modifier and adjunct. As a complement, the PP in Dholuo functions as object complement, verb complement, adjective complement, predicative complement and prepositional complement. as a modifier, it post modifies an NP while as an adjunct, the PP in Dholuo functions as an adjunct either of place or reason. With regard to our third objective, our analysis revealed that the PP in Dholuo theoretically lends itself to the X-bar theory schema. This study finally recommends that since the PP in Dholuo exhibits both simple structures like P+NP and complex structures like P+PP, the teaching of simple structures should come first especially in primary schools where learners are taught in the language of the catchment area because they are easy to understand before the complex structures are introduced progressively as the learners move to high levels.