OBJECTIVE It was to develop smoothed height and weight percentiles for boys and girls with IDs between 7 and 17 years old. METHODS The sample consisted of 1,047 young people (645 boys and 402 girls; 7-17 years old) with ID. A total of 4,059 measurements (height: n = 2,041; weight: n = 2,018) were retrospectively obtained from the period between 2013 and 2018. Smoothed height and weight percentiles were developed using the LMS method. Local and global diagnosis of percentiles were evaluated with Q statistics and detrended Q-Q plots. RESULTS Percentiles (5, 10, 25, 50, 75, 90, and 95) for height-to-age and weight-to-age were developed with satisfactory modeling in boys and girls between 7 and 17 years old. Boys showed a linear trend in height up to 11 or 12 years old, an increment from 13 to 15 years old and a deceleration from 15 or 16 years old. For the girls, height was linear between the ages of 7 and 11, followed by a deceleration from the age of 12 and without substantial changes from the ages of 15 to 17. Regarding weight, girls showed a linear trend of weight gain until the age of 13 and deceleration at the age of 14 or 15. Boys, however, showed a linear tendency to gain weight from 7 to 17 years old. CONCLUSIONS The height and weight percentiles developed in this study can help monitor the growth of young people with ID.