A careful review of the literature and an examination of desegregation programs in Los Angeles, show that the claim that voluntary programs produce almost no desegregation, and certainly less than mandatory programs, is open to question. Most comparisons between voluntary and mandatory programs have been between cities and have not taken into account variables such as differing demographic characteristics, the relative proportions of students in voluntary and mandatory transfers, the source of the desegregration plan, and the extent of the plan. The combination of voluntary and mandatory programs in Los Angeles provides an opportunity to analyze and compare the effect of voluntary and mandatory components within the city and also across cities. Analysis of Los Angeles' voluntary one-way transfer program, magnet school program, and a court-ordered desegregation plan shows that for blacks there is a larger differential effect of voluntary programs relative to mandatory reassignments in terms of (1) the percentage white school population for the average black student; and (2) the segregation index. There were some differences among elementary, junior high, and high school levels. For Hispanics and Asians, both types of programs had little effect. Other multi-ethnic cities show the same kind of results. These results, along with the fact that the change in the segregation index for blacks achieved by Los Angeles' voluntary measures exceeded the reduction in racial imbalance achieved by many court-ordered northern desegregation plans, shows that standard methods of comparison do not adequately address the issue of effectiveness. (CMG)