Testosterone plays a pivotal role in maintaining balance within the multi-dimensional psychological network of mood, behaviour, self-perception and perceived quality of life in men of any age. Apart from classical forms of hypogonadism, low testosterone concentrations can also be seen in older men, described as an age- and comorbidity-driven functional hypogonadism and might relate to depressive symptoms exhibiting a wide array of clinical pictures ranging from dysthymia and fatigue over inertia, listlessness to hopelessness and suicidal thoughts. Also, various traits of anxiety, from unfocussed fear to phobic anxiousness and open panic syndromes, are influenced by testosterone. Correspondingly, anxiolysis is likely to be modulated by testosterone via stress resilience, threat vigilance and reward processing. The steroid modulates pro-active and re-active dimensions of aggression, which has to be seen within the context of gaining or maintaining status. This may also include other strategies impacting the social position: heroic or parochial altruism and non-aggressive paths of assertiveness, such as posture and social vigilance. Independent rather than relationship-associated self-construal and self-esteem influence risk-taking traits under the modulation of testosterone. In addition, the genetic setting of the androgen receptor modulates the role of testosterone in aspects regarding mood and personality. Dimensions of sexuality are rather important in this context, but are not target of this article and covered in another part of this special edition. Overall, the quality of life in older hypogonadal men can be positively influenced by testosterone substitution, as has been demonstrated in large placebo-controlled trials.