Centre for Science and Environment (CSE), the New Delhi-based environment research and advocacy group, brings to you the first and only detailed technical guidance manual on CEMS in India, seeking to empower stakeholders with the knowledge of the best practices adopted around the world. It offers detailed information on available technology options, their limitations and suitability for various industries, quality assurance systems, correct installation techniques, proper operation and maintenance processes including calibration and drift check and data acquisition and transfer systems. The guidance manual also refers to various regulations and technical documents from Europe and the US which are widely used to illustrate best practices across the world. The manual is an effort to support the CEMS initiative of the Ministry of Environment, Forest and Climate Change (MoEF&CC) and CPCB; it should, therefore, be seen as supplementary to the CPCB guidelines on CEMS. CSE hopes that this guidance manual will help in skill and knowledge development of stakeholders and successful implementation of CEMS in India.