Aims One of the impairments evaluated in children with cerebral palsy (CP), which perhaps has been least investigated, is reduced selective motor control. The aim of the present study was to determine construct validity, discriminative validity, and intra- and interrater reliability of the Selective Control of the Upper Extremity Scale (SCUES). Methods Thirty-three children with unilateral CP, with a mean age of 11.5 +/- 3.3 years, at level I to IV according to the Manual Ability Classification System (MACS), participated. The children were video-recorded and scored using the SCUES. The videos were scored twice to determine the intra- and interrater reliability. Reliability was assessed using the intraclass correlation coefficient, the standard error of the measurement (SEM), and the smallest real difference (SRD). Differences in the SCUES scores were determined between the less- and more-affected arm and across all MACS levels for discriminative validity. Construct validity of the SCUES was established by the MACS, and the Jebsen Taylor Hand Function Test (JTT). Results SCUES scores were significantly different between the less- and more-affected arm (p< .001) and between the arm joints. SCUES scores were also significantly different among MACS levels (p< .001). The SCUES was strongly correlated with the JTT (Spearman's rho = -0.80,p< .001) and MACS (rho = -0.78,p< .001). Intra- and interrater reliability were excellent (intraclass correlation coefficient [ICC] > 0.75) for all joints of the more-affected extremity. The SRDs at the 95% confidence level for intra- and interrater reliability were 2.11 and 1.16, respectively. Conclusions The SCUES is a valid and reliable tool to assess selective motor control of the upper extremity in children with unilateral CP.