Neutron Cross Sections, Volume 1: Neutron Resonance Parameters and Thermal Cross Sections, Part A represents the fourth edition of what was previously known as BNL-325, Neutron Cross Sections, Volume 1. This three-chapter book provides the extensive list of detailed individual resonance parameters for each isotope. The first chapter deals with the thermal cross sections and average resonance parameters, as well as the physics of thermal and resonance neutrons, with particular emphasis on evaluation methods. This chapter also includes tables of standards of capture cross sections and scattering lengths, and commonly used nuclear physics formulas. The second chapter covers the direct or valence capture and the Brink-Axel treatment of electric dipole radiation. These topics are followed by a discussion on spin-dependent scattering lengths that are of interest to solid state. The third chapter describes the Maxwellian 30-keV capture cross sections that are of importance to studies of nucleosynthesis and age of the universe. This chapter also examines the s- and p-wave average radiative widths and gamma-ray strength functions that are required in capture cross section measurements. This book will appeal to nuclear and astrophysicists.