Objective To investigate the phonological development of toddlers from 2 to 3 years of age with complete unilateral cleft lip and palate (UCLP) treated during the first year of life with and without infant orthopedics (IO). Design In a randomized clinical trial (Dutchcleft), two groups of children were followed up: one treated with IO (IO group) and another that did not receive IO (non-IO group). Phonological skills were analyzed at 2, 2.5, and 3 years of age using a system for assessing phonological development of Dutch children (Fonologische Analyse van het Nederlands: FAN). The analysis included number of acquired consonants, order of phonological development, use of phonological processes, and occurrence of nasal escape. Patients Criteria for inclusion were complete UCLP, no soft tissue bands, no other malformations, parents fluent in Dutch, birth weight of a minimum of 2500 g, and gestation time of a minimum of 38 weeks. Interventions IO treatment based on a modified Zurich approach was started within 2 weeks after birth and used until soft palate closure at 12 months of age. Children in the non-IO group visited the clinic for an extra check-up at 6 weeks as well as before and after lip repair and soft palate closure. All other interventions were the same across groups. Results Phonological development of most 2.5-year-old IO children was normal or delayed. Most children in the non-IO group followed an abnormal developmental pattern. At age 3, the children in the IO group had acquired more initial consonants. There were no group differences in the use of phonological processes or the occurrence of nasal escape. Conclusions Children treated with IO during their first year of life followed a more normal path of phonological development between 2 and 3 years of age.