Sustainable behaviour, the set of effective and deliberate human actions aimed at conserving present and future earth's biophysical and social resources (Corral-Verdugo, 2010) is one of the main subjects of environmental psychology (EP). This is understandable because environmental problems have become so extreme that they pose a real threat to humankind's existence. EP studies the interactions between people's behaviour and their socio-physical environment (Aragonés and Amérigo, 2000). Some of these interactions result in ecological and social problems: Most of the depredations of natural resources, as well as human suffering are produced by negative people's actions. The daily behaviour of men and women, along with their psychological predispositions constitute the paramount causes of ecological and social disturbances. This book incorporates works of empirical research that are derived from different conceptual models based on psychological or psychosocial theory. It presents scientific studies on psychology, done principally by Spanish-speaking researchers from different countries.