Nationally, nearly one in five children younger than age 5 experiences multiple, concurrent child care arrangements. Yet, it remains unclear whether the use of multiple arrangements contributes to school readiness at kindergarten-entry, or whether these associations vary by the timing of multiple arrangements and the type(s) of care used. Using nationally-representative data (N=6450), this study estimated associations between experiencing multiple arrangements at ages 9 months, 2 years, and 4 years and children's school readiness in the fall of kindergarten. It also examined whether these associations depend on the type(s) of care combined. Results from OLS and propensity score weighted regression models suggest that multiple arrangements are associated with positive, neutral, or negative school readiness outcomes depending on both the timing and the type(s) of care used. (author abstract)