A study investigated properties of children's naturally occurring arguments. The arguments were sampled from transcripts of 20 discussions held in 4 fourth-grade classrooms. The principal findings were that children's arguments are filled with seemingly vague referring expressions; that the arguments sometimes do not contain explicit conclusions; and that the arguments almost never contain explicit warrants to authorize conclusions. However, the missing or obliquely identified information usually is given in the text or preceding discussion or is a commonplace from everyday life and readily inferable by actively cooperative participants in the discussion. Children seldom back their arguments by appealing to general principles, except when the foundation for the argument is disputed or seems confusing. At a more general level, findings suggest that it is possible to give a coherent account of children's arguments within the framework of informal deductivism augmented with speech act theory. (Contains 27 references, 1 note, and 1 table of data.) (Author/RS)