The study's aims were to (a) evaluate preschoolers' use of private speech (overt talk to themselves) during spelling; and (b) study how it is affected by the nature of orthography. Participants were 197 Hebrew speaking Israeli preschoolers (109 girls and 88 boys) (M = 5.6 years). Children spelled 12 words (N =44 letters) that represented one of three phonological word structures in terms of their consonants (C) and vowels (V): CV.CVC, CV.CV.CVC, and CVC.CVC. Children's private speech during spelling was documented and analysed. In this paper, we report the private speech units most frequently produced when spelling the letters correctly--CV, CVC, and letter name. When using private speech, children succeeded in correctly spelling a greater number of letters (30.69%) than when not using private speech (17.64%). The private speech across word structures primarily contained CV units and letter names. Children used private speech mostly for words' first letters and for CV.CVC words. The structure and position of the letters (first, second, last) had a combined effect on the production of private speech. CV units were used mostly in the first letter of CV.CVC words, CVC units in the second letter of a CVC.CVC word, and letter names in the first letter of CV.CVC words. These findings suggest that preschoolers are aware of the features of the orthography, as exemplified by their internal thought process when spelling words. Adults can support children's understanding of the written language by encouraging them to use private speech during word writing.