This book is designed to foster interdisciplinary understanding, information sharing, and integrative approaches to athlete assessment, mental training (MT), and outcome research in evidence-based applied sport psychology. Neurocognitive testing (NCT) and quantitative electroencephalography (qEEG) are brain assessment procedures that are used to investigate relationships between cortical functioning and context-specific outcome measures to arrive at clinical diagnoses or better informed patient and client evaluations. Research is ongoing to test the premise that NCT and qEEG can serve as reliable criterion-referenced measures for athletes profile primary higher order (AP PHO) constellations, heart rate variability (HRV) responding and eventually macro- and micro-performance outcome. The Polar heart rate variability (HRV)/heart rate deceleration (HRD) paradigm allows for more extensive and time-locked predictive validity statistical analyses so that in-the-moment MT over the course of entire official games/matches/competition can be delineated and quantified in terms of MT’s predictive validity. Behavioral-Motor-Technical (BMT)-based intervention attempts to help support an athlete’s mental game using exposure, confrontation, threshold, and learning principles to improve attention, motor control, and self-confidence, as well as reduce nervousness associated with pressure moments of competition. The goal of BTM-MT is to consolidate optimum technical and motor patterns in long-term procedural memory as well as repetitively attempt to demonstrate peak technical performance under greatest situational pressure, first in training and then during official competition. The book also provides a foundational and fundamental rationale for advancing evidence-based and validated athlete assessment and intervention protocols.