Diversity is core to what makes many cities vibrant, dynamic, adaptive and strong. Recently, Boston has gotten much more racially diverse, evolving from being only 20 percent people of color back in 1970 to 56 percent of color today. However, there's a way in which the rich tapestry of the city has eroded: Boston is rapidly losing families with children. In particular, it's losing families with K-12 school-aged kids. Boston has experienced large declines among Black and white kids; significant Latino increases have offset some of these decreases, but only partially. The families who leave Boston when their kids approach kindergarten are predominantly middle and high income. This has created a growing mismatch between the demographics of kids who attend Boston's K-12 public schools and the city overall. This report dives deep into these trends in three parts by analyzing: (1) Boston's declining school-aged population; (2) the growing mismatch between city and school demographics; and (3) the increasing isolation of students of color and low-income students in Boston schools. The authors hope this demographic analysis will help accelerate public conversations about how Boston can welcome all families back to the city and promote greater economic and racial integration in the schools. [This report was co-produced by Boston Indicators.]