The Infant Toddler Activity Card Sort (ITACS) is a new measure that engages caregivers in goal development by measuring participation in early childhood. Initial evaluation of the ITACS is required to assess its psychometric properties. To evaluate test–retest reliability, concurrent validity, and between-group differences of the ITACS. Caregivers ( N = 208) of children 0–3 years, who were typically developing (TD) or had a developmental delay (DD), completed the ITACS and Pediatric Evaluation of Disability Inventory–Computer Adaptive Test (PEDI-CAT) with repeat assessment after 2 weeks later ( n = 117). The ITACS demonstrated moderate concurrent validity with the PEDI-CAT. Children with DD had significantly more activity concerns on the ITACS than TD. Adequate test–retest reliability was not achieved. The ITACS is a useful tool for identifying caregiver concerns in activity engagement; interventions can be tailored to address concerns and increase participation in childhood routines.