The use of real or near real time measurement of chemical production process parameters as the basis for achieving control or optimisation of a manufacturing process has wide application in the petrochemical, food and chemical industries. Process analytical chemistry (PAC), or process analytical technology (PAT) as it has recently been called, is now being deployed in the pharmaceutical industry, where it is seen as a technology that can help companies to improve their conformity with manufacturing compliance regulations. The objective of this book is to provide a starting point for implementing process analytical chemistry tools in process monitoring applications or as part of a total quality management system. Written from the perspective of the spectroscopist required to implant PAT tools in a process environment, attention is focussed on measurements that are made “in process” at-line or off-line, providing data on product during manufacture. With chapters covering the key spectroscopic tools, their applications in the pharmaceutical and chemical industries and basic chemometrics, the novice can quickly develop a sound understanding of the most practical technologies and applications. Implementation strategies are fully covered and address some of the critical issues that need to be tackled when setting up a PAT project – including choosing a project with a sound business justification in the first place.