Assuming that learning to spell and punctuate involves making and testing hypotheses about how the orthographic style of English works, a study explored six children's classroom spelling during their third and fourth grade years. The subjects were American children of the Tonono O'odham (Papago) tribe of southwestern Arizona who were part of a larger study on writing development in children. Researchers visited the classrooms weekly, observed the children writing stories, videotaped writing episodes, and conducted interviews with the children on their conceptualization of the writing process. The 215 stories were compared for percentages of conventional and nonconventional usage for spelling and punctuation, and for patterns of nonconventional use. Findings showed that (1) high frequency words were almost always spelled conventionally, while words used only once were spelled conventionally about half the time; (2) spelling features that were less frequent, less predictable, or more abstract tended to present more difficulty; (3) spelling generally improved from third to fourth grade; (4) most invented spellings involved reasonably successful efforts to represent phonology; (5) punctuation was appreciably more difficult than spelling for these subjects, with punctuation supplied as needed only 55.6% percent of the time, and conventional spelling provided 86.3% of the time; (6) some punctuation marks were more difficult than others, with periods and question marks provided at least half the time, commas and quotation marks usually omitted; and (7) punctuation improved dramatically from third to fourth grade, despite little instruction other than the practice of writing. Interviews with two of the children showed that most idiosyncratic patterns involved understandable conceptual strategies. A five-page list of references concludes the document. (JG)