Boston Mayor Martin Walsh wants to double the number of 4-year-olds in the city enrolled in early education programs within four years.

Walsh announced on Tuesday that he's asked an advisory committee to come up with a plan by November for increasing access to pre-kindergarten programs.

Walsh said about 25 percent of the city's 4-year-olds are not in any kind of pre-kindergarten program, either through the Boston public schools or in a community setting.

There are currently about 6,000 children in that age group in Boston, with the number expected to grow in the coming years.

Walsh says research shows access to early education programs with trained teachers leads to stronger academic performance in the future, and reduces the achievement gap for lower-income students by the third grade.