*LAST CALL* Dear Stable Isotope Community, Please consider submitting an abstract for session 12a "*A Remarkable Legacy of Advancements in Stable Isotope Geochemistry: A Session Honoring the Career of Karlis Muehlenbachs* at Goldschmidt 2024, 18-23 August, in Chicago, Illinois, and help us celebrate Karlis' incredible contributions to stable isotope geochemistry on the occasion of his 80th birthday! *Keynote speaker: *Karlis Muehlenbachs *Session description:* This session will celebrate the distinguished career of Karlis Muehlenbachs, a trailblazer in the field of stable isotope geochemistry and a pioneering contributor to our understanding of the oxygen isotope composition of seawater and hydrothermal systems. For more than 5 decades, his groundbreaking research has significantly advanced our knowledge of Earth's processes and has left an indelible mark on the scientific community. From his seminal contributions to understanding the oxygen isotope composition of seawater to his extensive studies on hydrothermal systems, ore deposits, petroleum systems, amber, and ancient life, Karlis continually applies innovative approaches that have enhanced our comprehension of the processes occurring in these dynamic environments, shedding light on the intricate interplay of geochemical reactions. This session welcomes contributions from researchers, collaborators, and mentees to present their work and share personal reflections on Karlis’s profound influence. Presentations will highlight the enduring impact of his extraordinary career, providing an opportunity for the scientific community to reflect on his contributions and inspire future generations of geochemists. *Abstracts are due on March 29. No late submissions will be accepted.* All pertinent information can be found here: https://conf.goldschmidt.info/goldschmidt/2024/goldschmidt/2024/meetingapp.cgi *IMPORTANT*: The Democratic National Convention is taking place at the same time in Chicago so hotels are filling up quickly. Book your accommodations now! Looking forward to seeing you in Chicago! For the Organizers: *Neil Banerjee, James Farquhar, and Keiko Hattori*