The Passive Sampling Update Guidance Document combines the previous ITRC Passive Sampling documents (DSP-1, DSP-3. DSP-4, DSP-5) along with updates to the technologies into one comprehensive document that evaluates 24 passive sampling technologies. The document explores the use of these technologies and application of the data gathered to all phases of environmental remediation. This document is intended to be used by regulators and stakeholders currently sampling environmental media at sites undergoing evaluation, remediation, or monitoring for compliance with applicable laws and regulations.