The Chicago Climate Action Plan is a comprehensive sustainability plan that can inspire public participation, allow city departments to see how their existing green activities fit into a broader agenda, and provide a roadmap for what businesses and individuals can do. The Plan focuses most on how action will sustain a high quality of life for the people of Chicago by improving public health and the resilience of natural areas; lowering energy costs and creating jobs in emerging high technology sectors; increasing the comfort and efficiency of buildings, as well as the reliability of energy services; and broadening transportation choices, including higher quality transit and better access to services in greener neighborhoods. It describes how the City will protect its people from climate changes that are no longer avoidable, such as hotter summers, more heat waves and more severe storms. Many of the actions solve multiple problems and build on the success of one another. Last, but not least, the Plan offers a way to quantify, track, and publicly share progress. This document builds off of the Climate Action Plan process and provides readers with key lessons learned during the process. This resource provides a summary of lessons learned from the Chicago Climate Action Planning process, observations from each phase of the process (research, planning, and implementation), and more. This resource can be used in tandem with the other resources that were developed through this process to provide practitioners and planners with an example of how the action planning process can be effectively completed.