This book offers practical insights for the study of intraspecific genetic variation in crustaceans. Combining theory and case studies, it helps researchers select methods of analysis and interpret their results. The theory chapters discuss the potential of currently used and upcoming molecular markers in the context of marine non-model species. Case studies of marine and limnic crustaceans highlight the importance and diversity of sources of population structure in intraspecific variation. Throughout, the book showcases the use and analysis of molecular markers, including mitochondrial and nuclear DNA sequence data, coding and non-coding sequences, microsatellites, and cytogenetics.