The objective of this study was to identify causal relationships between the development of phonological abilities and progress in writing in preschool children. The participants were 44 children, with an average age of 5 years and 6 months, and whose writing was syllabic with phonetization. The children were divided into three groups. They were subjected to a pre-test and a post-test that were intended to evaluate both their writing and their phonological skills. In between the two tests experimental group 1 underwent a writing training program designed to lead them to produce syllabic-alphabetic/alphabetic writing, while experimental group 2 was subjected to a phonological training program designed to work on phonetic units. The third group served as a control group. The number of letters known and the level of intelligence were controlled. The children in the two experimental groups achieved results that revealed a similar degree of progress (greater than the control group) in both their writing and their phonological abilities. (Contains 8 tables and 2 figures.)