This thesis seeks to add to the psychological literature that may help reduce global poverty and human rights abuse around the world. More specifically, it investigates the potential role of psychological flexibility and Acceptance and Commitment Therapy (ACT) in helping to increase “global freedoms”. It makes a unique contribution through the way it applies psychological flexibility and ACT to this novel area. Following two introductory chapters, the next five describe the design and preliminary evaluation of new self-report measures. Specifically these assess: i. helping behaviour, ii. thoughts and cognitions, iii. feelings and emotions, and iv. values – all related to global freedoms. A fifth scale measures psychological inflexibility in an everyday context. Preliminary psychometric development includes both exploratory and confirmatory factor analysis. Following their development, the measures are used to answer five research questions. In general terms these explore the interrelationships between the measures; how they relate to helping behaviour and whether psychological flexibility plays a direct or indirect role in this. The research questions are answered using a cross-sectional dataset as well as a single session, lab based study which examines the potential of an ACT based intervention to increase helping behaviour. In summary, in both correlations and regressions, the thoughts and cognitions measure had a significant, negative correlation with helping behaviour, while the feelings and emotions, and values measure had significant, positive correlations with helping behaviour. Psychological flexibility did not show a significant, direct relationship with helping behaviour but, in mediation analyses, it was found to transmit its influence through thoughts and cognitions onto helping behaviour. In terms of the single session lab based study, neither ACT nor an education condition increased the level of donation to charity greater than a control. The general discussion focuses on the implications of these findings and the opportunities for future research.