Using 14.7-MeV neutrons and gamma-ray spectroscopy with high-purity germanium detectors, the activation cross sections have been measured for the following nuclear reactions: (a) 44Ca(n,p)44K, = (39 ± 4) mb; (b) 44Ca(n,np)43K, = (3.0 ± 0.3) mb; (c) 44Ca(n,)41Ar, = (31 ± 3) mb; (d) 42Ca(n,p)42K, = (138 ± 12) mb; (e) 43Ca(n,p)43K, = (90 ± 9) mb; and (f) 48Ca(n,2n)47Ca, = (613 ± 60) mb. A 98.6% enriched 44Ca target was used for reactions (a), (b), and (c) and a natural calcium target for reactions (d), (e), and (f). These cross sections have been compared with some earlier published experimental values and with some results of calculations. The latter include those based on semiempirical formulas and those given by the preequilibrium plus compound-nucleus code GNASH. When applied to reactions (a), (d), (e), and (f), this code gives cross-section values that are consistently above the measured values.