A study examined developmental trends in the quality and outcomes of disagreements occurring in the conversation of small groups of acquainted peers. Specifically, the study focused on the relationship of disagreeing and arguing sequences to the general level of topical coherence achieved in the conversation as a whole. Five discussion groups, each composed of three females and three males, were formed at each of five grade levels--second, fifth, ninth, twelfth, and college. The eighth meeting of each group was transcribed and turns of talk were coded for topical coherence and argumentation. The results suggested that the development of argumentation is closely related to the development of norms pertaining to topic. Developmental trends in the quality of disagreeing and arguing closely paralleled trends in the topical coherence achieved by a group as a whole. In addition, where norms pertaining to topic were weak, argument was less well-modulated, and where the norms pertaining to topic were stronger, argument conformed to the norms. Adolescents' and adults' conversations contained a lower proportion of disagreements, briefer sequences of disagreements, and fewer insults than did those of young children. (Samples of topical coherence categories and extensive tables of data are appended.) (FL)