Treiman's major focus is on reading and spelling skills and how they develop. One line of research examines children's spelling, including the linguistic reasons why children spell words as they do and how even the productions of very young children may show more knowledge than appears on the surface. Other research looks at children’s knowledge about letters and ability to decode written words. In addition, Treiman and her collaborators examine reading and spelling processes in adults. Many of the studies are carried out with learners and users of English, but some studies involve users of other languages.