Guidelines for Cloud Seeding to Augment Precipitation, Second Edition, provides practical details of what is involved in using the cloud seeding technology. This Manual of Practice incorporates pertinent background on the science and practice of weather modification by cloud seeding to augment precipitation. The sections of this manual include the societal, environmental, and economic aspects of precipitation enhancement by cloud seeding, legal aspects associated with weather modification operations, scientific basis, cloud seeding modes, and instrumentation and status of precipitation enhancement technology. Also included is an executive summary, which deals with the complex issues that arise with the development and application of the cloud seeding technology. It is intended to provide water resources managers and others with the information and references needed for decision making regarding the use of cloud seeding to augment available water supplies.