The use of molecular methods to study genetic polymorphisms has made a familiarity with population genetics essential for any biologist whose work is at the population level. "A primer of Population Genetics", third edition, provides a concise but comprehensive introduction to population genetics. The four chapters of the book address genetic variation, the causes of evolution, molecular population genetics and the genetic architecture of complex traits. Chapter-end problems reinforce ideas and, while there are some equations, the emphasis is on explanation rather than derivation.