A detailed assessment of the average class size in Massachusetts public schools is provided in this report, which includes the means and ranges of average class size and a description of class size across grade levels, subject area, and community type. Data were collected from the Chapter 188 Individual School Report (1987-88), an annual survey of Massachusetts public schools conducted by the State Department of Education. Section 1 provides background information on research related to class size, and section 2 describes statewide class size data by grade level, subject area, and type of community. Implications for policy making are discussed in the third section, and methodology is described in the final section. Seven figures and seven tables are included. (LMI)