In this book, light elements from Li up to Si for (?,n) reactions and from H to Al for (p,n) reactions, as well as ?-particle and proton energies up to 10 MeV are covered as far as the data of reaction cross sections are available. The cross sections altogether with the stopping powers calculated from the Zeigler formula have been used to measure the n-yields for each reaction and then the weighted averages (W.A.) have been calculated. The adopted n-yields are found to be in good agreement with the available data of previous studies. Empirical formulae are proposed for the evaluation of these W.A. n-yields of both (?,n) and (p,n) reactions. These formulae are based on empirical fits to the adopted n-yields calculated in the bombarding energy range from threshold up to 10 MeV.