The Canadian Society for Exercise Physiology (CSEP), in cooperation with ParticipACTION and other stakeholders, and with support from the Public Health Agency of Canada (PHAC), has developed the new Canadian Physical Activity Guidelines for Children (aged 5–11 years), Youth (aged 12–17 years), Adults (aged 18–64 years), and Older Adults (aged ≥65 years). The new guidelines include a preamble to provide context and specific guidelines for each age group. The entire guideline development process was guided by the Appraisal of Guidelines for Research Evaluation (AGREE) II instrument, which is the international standard for clinical practice guideline development. Thus, the guidelines have gone through a rigorous and transparent developmental process; we based the recommendations herein on evidence from 3 systematic reviews, and the final guidelines benefitted from an extensive online and in-person consultation process with hundreds of stakeholders and key informants, both domestic and international. Since 2006, the products of our efforts resulted in the completion of 21 peer-reviewed journal articles (including 5 systematic reviews) that collectively guided this work. The process that Canadian researchers undertook to update the national physical activity guidelines represents the most current synthesis, interpretation, and application of the scientific evidence to date.