This chapter reports the quantitative investigation of psychological mindedness (PM) in executive coaching effectiveness using the CES. The study employed Classical Test Theory to assess the scale’s psychometric properties and examine PM’s predictive role. Data from a large-scale survey, including the CES and the Psychological Mindedness Scale, were analysed using reliability, validity, factor analysis, regression, and correlational models. Results confirm the CES as a reliable, valid measure of coachee-perceived outcomes across seven domains. PM emerged as a significant predictor, highlighting the role of self-reflection and awareness in maximising coaching benefits. These findings advance evidence-based coaching research and inform coachee selection and development in organisational contexts.