The 2018 joint 14th iCACGP Quadrennial Symposium and 15th IGAC Science Conference (iCACGP-IGAC 2018) was held 25-29 September 2018 in Takamatsu, Kagawa, Japan. iCACGP-IGAC 2018, with the theme “Atmospheric Chemistry: From Molecules to Global Impacts”, provided a platform for exchanging information and new ideas on the current scientific knowledge on atmospheric chemistry and its connections to climate change, policy, and other important interdisciplinary work. Overall iCACGP-IGAC 2018 was a huge success with 733 participants representing 46 different countries. Early career scientists represented 40% of the attendees, highlighting vibrant and active research.