This study sought to examine the influence of transcription skills, evaluated using graphonomic measures, on the proficiency of text generation in students attending primary schools in Spain. A longitudinal design was employed involving 278 Spanish students distributed across three cohorts (cohort 1: 1st-2nd-4th grade; cohort 2: 2nd-3rd-5th grade; and cohort 3: 3rd-4th-6th grade). Two data collection points were used to administer the graphonomic measures, and a composition letter task was conducted at the conclusion of the study. Four multigroup structural equation models were employed, examining the direct pathways from graphonomic measures (i.e., pressure, speed, pauses, and road length) on text generation (i.e., length, fluency, planning, revision, and organization). The models demonstrated a good fit to the data. The findings from the four models, analyzed within the three cohorts, indicated that the significant effect of transcription (i.e., handwriting) on text production was primarily observed in Cohort 1 (early grades), while no significant effects were found in Cohort 2 (intermediate grades). This suggests that the importance of handwriting in text production in a transparent orthography may be more pronounced during the initial stages of writing development when students are acquiring foundational writing skills.