We comprehensively review the current state-of-the-art of environmental monitoring for hydrophobic organic contaminants in aqueous matrices using passive sampling devices. Principles of the theory of passive sampling are presented. Strategies for passive sampler design and operation, limitations in performance and data quality-assurance and quality-control are reviewed. Advances in applications of available passive sampling devices are extensively critiqued. Future trends and current challenges facing practitioners and barriers to further adoption of the devices are discussed.