Non-targeted analysis (NTA) using high resolution mass spectrometry is rapidly gaining popularity as a tool for environmental monitoring. This talk will explain the basic principles of NTA from hardware and data acquisition through to data processing and reporting. Specific topics will include: (1) data dependent (DDA) versus data-independent acquisition (DIA); (2) data mining strategies – targeted screening, suspect screening, and non-targeted screening; and (3) tools for compound identification, and reporting levels of confidence.