Most models of spelling assume that people rely on two procedures when engaging in spelling: a lexical look-up procedure that retrieves spellings in their entirety, and a nonlexical procedure that constructs spellings with a set of phoneme-grapheme rules. In the present research, we investigated whether larger sized subsyllabic relationships also play a role in spelling, and how they compare to small-sized phoneme-grapheme relationships. In addition, we investigated whether purely orthographic units can explain some of the variance typically attributed to the mapping between sound and spelling. To do this, we ran five spelling experiments, two using real words and three using nonwords. Results from the experiments showed that there were independent contributions of both phoneme-grapheme and larger sized subsyllabic sound-spelling relationships, although the effect of phoneme-grapheme-sized relationships was always stronger and more reliable than larger sized subsyllabic sound-spelling relationships. Purely orthographic effects were also shown to affect word spelling, but no significant effects were found with nonword spelling. Together, the results support the hypothesis that a major constraint on spelling comes from phoneme-grapheme-sized relationships.