This study assessed the impact of a positive psychology intervention in a sample of 40 young men (35%) and women (65%) aged 18-30 years. Participants were 1st and 4th year undergraduate University students, postgraduate students and working youths. The study examined the effects of a battery of interventions commonly used in positive psychology interventions, including a video and three exercises (i.e. expressing gratitude, best possible selves, goal setting) on character strengths, hope, gratitude and social relations. Intervention activities were carried out during a session that lasted an hour and a half, while a further half-hour evaluation session took place after a two-week interval. Marked positive changes were revealed with regards to youths’ well-being as a result of the intervention. In particular, elevated levels of hope, perceptions of social support and ability to handle social stress successfully, as well as levels of three out of six key character strengths, i.e. courage, humanity/love and transcendence were observed. Influences of demographic and socio-psychological characteristics of youths on the above variables; constellations of intricate relations between them; as well as certain developmental patterns were also highlighted. The repercussions of the above findings for the advancement of positive psychology knowledge and interventions are discussed.