Lesser is chairman of the Children's Television Workshop's board of advisers which shaped and tested the content of what might be the cool medium's hottest -- and happiest -- hour; this is an admittedly (but disarmingly) partisan history of Sesame Street's development from Barbara Cooney's initial proposal for a TV show to supplement and extend existing preschool education. Despite the criticism by John Holt and others, the board (mostly experts in education and psychology but also including such creative talents as Maurice Sendak) agreed that restructuring American education was beyond their scope and that helping to prepare poor children to take advantage of the education that exists would be their fundamental purpose. Lesser credits unprecedented cooperation between the advisers and the creative staff -- ""the boldest experiment of all"" -- with the show's success in teaching through format as well as content, and the few examples he supplies here are enough to reassure nonviewers concerned that the show was being researched to death. In terms of numbers Sesame Street was of course a spectacular success; the researchers' problem became one of finding nonviewers for controls in their ongoing tests. Progress toward the Workshop's specific instructional goals was almost as impressive, though regarding the crucial question of influence on school performance, Lesser reports only that all 160 tested former viewers were ranked higher than nonviewers by their kindergarten and first grade teachers in all areas of school readiness. For Lesser the lesson of Sesame Street is that a program with undisguised educational aims can attract and teach a large and loyal audience of preschoolers; as to what the program is not -- he considers, not without occasional pique, all of the inevitable negative assessments from the accusation that the show promotes integration (""we do"") and communism to the fatuous assertion that no adult has the right to decide what children should learn. Lesser's hope is that the show will in the '80's be looked on as the horse and buggy stage of educational television. Perhaps the Workshop's biggest disappointment is its failure to stimulate commercial channels to corresponding efforts.