TO BE effective, preschool teachers need crayons, well-stocked classrooms, and college educations. But a new study says that the state's public and private colleges don't have enough resources to teach the preschool teachers. It's a troubling lack of capacity just as Massachusetts is trying to build a statewide system of early education and care.

Preschool is a juggling act of teaching social, emotional, cognitive, and physical skills: how to cut and paint as well as how to listen and share. Activities have to be compelling to keep and win the attention of very young children.

Unfortunately, there are more teachers in need of college degrees than there are college seats. According to a report by the Wellesley Centers for Women, 46 percent of the state's 14,000 teachers of 3- to 5-year-olds lack college credentials. The report estimates that, given existing capacity, it would take seven years for the current corps of teachers to earn associate degrees and 19 years to earn bachelor degrees. This assumes that all teachers are college-ready and that they would attend classes full-time. In fact, some teachers would have to build their English skills, and others would only attend college part-time. But the estimate sends a warning: To educate more of its young children, Massachusetts has to educate more teachers of young children.

It's a job for public and private colleges, especially in western and southeastern Massachusetts, where the need is great.

Once teachers have their degrees, they deserve salaries that reward their progress and make it attractive for them to work in early education. They also need continuing education and career ladders that let them grow as professionals. Special attention should be paid to providers who offer care in their own homes: 56 percent don't have college credentials, according to the Wellesley report, though they tend to provide most of the care for infants and toddlers.

The United Way of Massachusetts Bay recently highlighted another imperative: a diverse group of teachers and administrators to meet the needs of diverse families, including children who speak English as a second language. Massachusetts needs a workforce development system that raises the quality of early education and care and builds the state's great academic wealth.