This special issue seeks to address the stagnation in mental health treatment efficacy by moving beyond a "one-size-fits-all" approach. It invites tutorial-style submissions on advanced statistical methods for personalizing treatment and evaluation. The goal is to bridge the gap between research and practice by making new methods accessible to a wider audience, including clinicians. Submissions should be practical, with case demonstrations and open materials to enhance replicability. The issue emphasizes the importance of translating research insights into clinical practice to improve patient outcomes and shape the future of therapy.