Prior theoretical models and empirical research suggest that specific parent, child, and family factors are related to the utilization of early childhood education and care (ECEC). The political context of Norway provides a unique opportunity to test whether increased availability and affordability of care over time due to policy change reduces the gap between high- and low-socioeconomic status (SES) families in utilizing center-based care compared to other care arrangements. Progressive Norwegian child care policies were also expected to reduce the effect of child and family characteristics that might make a family less likely to enroll their child in center-based care. Using a large sample from the Norwegian Mother and Child Cohort Study (MoBa, n?=?60,270), this research examined selection factors predicting enrollment in center-based ECEC at age 18 months across cohorts from 2002 to 2006. While families with higher parental education and income-to-needs ratios were more likely to enroll their children in center-based care, the progressive universal child care policy did succeed in reducing the utilization gap between the most and least educated families across time. The policy appeared to be protective against the effect of most other factors predictive of ECEC use, but the high number of children was still associated with underutilization.