Past research shows that time spent in developmental care activities has been increasing in the United States over recent decades, yet little is known about how this increase is distributed across parents with different levels of education. Have children born into different socioeconomic groups been receiving increasingly equal developmental care from their parents, or is the distribution of parental time investment becoming more unequal? To answer this question, the author analyzed the American Heritage Time Use Study (19652013) and showed that the gap between high- and low-educated parents' time investment in developmental child care activities has widened. An increasing absence of fathers in households with low-educated mothers has exacerbated the trend. This study documents growing inequality in parental time inputs in developmentally salient child care activities in the United States.