The objective of this study was to examine the development of derivational morphological structures in the productive language of Kuwaiti Arabic (KA)-speaking children. Participants were 512 typically developing Kuwaiti children aged 3;0 years to 7;11 years (243 boys and 269 girls). Five age groups at 1-year intervals were tested; each group was divided into four sub-groups at 3-month intervals. The children were examined using a tool designed to assess structures specific to the KA dialect, and they were assessed by trained research assistants at their nurseries and public schools. There were clear developmental trajectories in the derivational morphological structures studied in KA-speaking children across the five age groups. Results showed that KA-speaking children have not reached mastery level in most of the structures examined in this study. Among the two types of derivations examined, nominal derivations emerged later than verb derivations. Error analysis showed that most errors were morphological, affecting mainly the root. The results of this study enhance our knowledge of early language development in Arabic by showing that nominal derivations develop later than verb derivations. The results are discussed in light of previous cross-linguistic studies, which also found a similar trajectory in terms of morphological development. Further, Arabic morphological theory, as well as implications for practice and the need for further research, is discussed.