The Escala de la Calidad del Desempeño Sensoriomotor (ECDSM2-15) identifies the quality of sensorimotor performance in infants aged 2 to 15 months old, previously identified with motor delay (MD), or at risk/diagnosed with cerebral palsy (CP) on six subscales. It classifies the strategies infants use during functional motor behaviors as typical, delayed, or atypical, identifying the influence of alignment, movement, and base of support components.To adjust the cutoff points of the percentile areas and determine the sensitivity to change on the sensorimotor performance in the six subscales.Intentional samples of 1,432 infants for the percentile area adjustment and 371 infants for sensitivity to change were recruited from three child rehabilitation centers in Chile. Summary measures were calculated to establish the percentile area limits. For sensitivity to change, the corresponding age group subscale was administered twice to each infant with a 6-week interval. For the analysis, the Wilcoxon and δ Somers test were applied with a significance of p <0.05.Five sensorimotor performance areas are established: atypical, mildly atypical, delayed at risk of atypical, delayed, and typical. The sensitivity to change in all age groups is significant.The ECDSM2-15 classifies infants with MD or at risk/diagnosis of CP in five percentile areas of sensorimotor performance and is highly sensitive in detecting changes in sensorimotor functional performance, results that contribute to increasing its reliability.