Effective ground control in the gate entries is essential for safe and productive longwall mining. Longwall pillars protect the gate entries from the severe abutment loads that develop as the longwall retreats. This U.S. Bureau of Mines report summarizes 5 years of research aimed at improving longwall pillar design. Its goal is to provide longwall operators with practical procedures for maintaining longwall ground control. The report focuses on the analysis of longwall pillar stability (alps) design method, which was developed largely by Bureau researchers. With alps, mining engineers can estimate the strength of longwall pillar systems and the load that will be applied to them. Several other methods that can be directly used to size longwall pillars are also described. The design methods are evaluated using a data bank of more than 100 mining case histories, and suggestions are given for using the methods in practical design. A step-by-step solution to a sample problem using alps is provided. The report also discusses the theory and practice of yield pillar design and suggests strategies for special conditions, including soft floor, excessive horizontal stresses, and multiple-seam interactions.