In this paper we discuss the distribution of tones in Boro especially in the context of its derivational and inflectional morphology. While it is well known that Boro has two tones, Low and High, the way the tones are governed by word formation processes is not very well known. We show that Boro has some affixes which have their own tonal specifications. Among these tone bearing affixes, only the prefixes impose their tonal specification of the stem. Although some suffixes are found to have lexically specified tones, their addition do not alter the tonal nature of the stems. We also discuss how Boro tonal assignment is minimally in the domain of the minimal word and maximally in the domain of a prosodic word and show from trisyllabic domains that the prosodic word domain is preferred over whole word domains for tone assignment.