The second edition of Atoms, Radiation, and Radiation Protection has several important new features. SI units are employed throughout, the older units being de-fined but used sparingly. There are two new chapters. One is on statistics for health physics. It starts with the description of radioactive decay as a Bernoulli process and treats sample counting, propagation of error, limits of detection, type-I and type-II errors, instrument response, and Monte Carlo radiation-transport computations.