The question is frequently asked: How would a change in the half-life of C14 affect the Maya calendar correlations? The optimum “effective” half-life value for this era, as determined by the Pennsylvania measurements of contemporaneous samples of known age, and, as pointed out by Satterthwaite and Ralph (1960), is, by coincidence, very close to the Libby half-life (5568±30 years). Nevertheless, a change in the value of the half-life of C14 would not necessarily change the “effective” half-life, and, on the basis of present data, no change should be made in the University of Pennsylvania dating of the Maya calendar correlation samples.