The unambiguity with which some nuclear reactions may be identified often permits their use as highly sensitive and selective analytical tools for the determination of trace element concentrations in complex materials. In this report examples are given of the use of charged particle-induced nuclear reactions in attacking particular problems in astrophysics and planetary science. These problems include the determination of elemental abundances of boron and flourine in carbonaceous chondritic meteorites, the identification of products of lunar vulcanism, and the study of solar wind-implanted atoms in lunar materials. This technique will be seen to be an important supplement to other methods of elemental and isotopic analysis — especially for cases involving light elements at very low concentrations and where high resolution depth distribution information is needed in non-destructive analyses.