This manual was developed for use by local law enforcement agencies to assist them in all aspects of security planning and operations for dealing with large-scale security events. The manual was developed through the collaboration of the Bureau of Justice Assistance and CNA Analysis & Solutions, an organization that provided technical assistance and on-site technical support at both the 2012 Democratic and Republican national conventions. The manual synthesizes best practices related to security planning for a large-scale event in the following areas: pre-event planning, core event operations, and post-event activities. Detailed information is provided on 18 core operational areas, along with major findings learned from the work of police departments that have handled such events in the past. The findings are presented along the following areas: planning, finances, logistics, operations, and command of a large-scale security event. Some of the findings include developing a strategic vision centered on establishing a friendly and safe environment, creating a core planning team, conducting formal and informal meetings with stakeholders, beginning planning with careful attention to reimbursable costs, not underestimating the large scope of caring for visiting officers, and providing officer training and using only proven and pre-established technologies. Included in the appendixes is a planning toolkit for use by law enforcement agencies. Tables and figures