Our aim was to analyze the impact of the characteristics of occlusive versus fricative phonemes used in writing programs on the evolution of preschool children's writing. The participants were 39 5-year-old graphoperceptive children. Their intelligence, number of letters known, and phonological skills were controlled. Their writing was evaluated in a pretest and a posttest using words beginning with fricatives and occlusives. Between the two tests, experimental Group 1 trained the associations between letters and occlusive phonemes and experimental Group 2 between letters and fricative phonemes. The control group classified geometric shapes. Both experimental groups achieved better results than the control group. There were no differences between the experimental groups concerning the use of F, V, Z, and P; but experimental Group 1 achieved better results for B and D. The program that led children to think about the relationships between speech and writing under linguistically more complex conditions, which involves the mobilization of occlusive phonemes, seems to be more effective in the generalization of phonetization procedures than the program that mobilizes phonemes that are easier to isolate within the acoustic flow, such as fricative phonemes.