The annual high school contests have been sponsored since 1950 by the Mathematical association of America and the Society of Actuaries, and more recently by Mu Alpha Theta (1965), the National Council of Teachers of Mathematics (1967) and the Casualty Actuarial Society (1971). Problems from the contests during the period 1950-1960 are published in Volume 5 of the New Mathematical Library, and those for 1961-1965 are published in Volume 17. The New Mathematical Library will continue to publish these contest problems from time-to-time; the present volume contains those from the period 1966-1972. The questions were compiled by Professor C.T. Salkind until his death, and since 1968 by Professor J.M. Earl, who died on November 25, 1972 after submitting problems for the 1973 contest. Professors Earl and Salkind also prepared the solutions for the contest problems. In preparing this and the earlier Contest Problem Books the editors of the NML have expanded these solutions and added alternative solutions.