In this study, the authors explore the effects of an executive coaching programme on important performance psychology variables (self-efficacy, causal attribution, goal setting, and selfdetermination). One hundred and forty-four executives and middle managers from a Fortune high-tech 500 company participated in the experiment over a period of one year. Twenty executives participated in an external executive coaching programme and one hundred and twenty four middle managers participated in a coaching based leadership programme. Findings indicate that there are significant effects of external coaching on psychological variables affecting performance such as self-efficacy, goal setting, intra-personal causal attributions of success and need satisfaction. Findings also indicate that there are significant effects of coaching based leadership on self-efficacy among middle managers. However, the effects regarding coaching based leadership are not as strong as those from external executive coaching.