Dear colleagues! Optimization 2026 is the 11th edition of a series of Optimization international conferences held every three years, in Portugal, see https://optimization2026.iseg.ulisboa.pt/ This meeting will be held at ISEG, University of Lisboa, July 20-22, 2026, and aims to bring together researchers and practitioners with common interests in optimization. This conference series has international recognition and is being organized under the auspices of APDIO (the Portuguese Operations Research Society). Plenary speakers will be: Adam N. Letchford | Lancaster University, United Kigdom Boglárka G-Tóth | University of Szeged, Hungary Claudia Archetti | University of Brescia, Italy Dick den Hertog | University of Amsterdam, Netherlands Gabriela Eichfelder| Technische Universität Ilmenau, Germany Tom Van Woensel | Eindhoven University of Technology, Netherlands You are most welcome to propose a Special Session with 3 or 4 talks. Abstract submission deadline or Session proposal: 10 April 2026, https://optimization2026.iseg.ulisboa.pt/submissions.php Looking forward to meeting you in Optimization 2026!