Leisure time plays a great part in the lives of adolescents, especially in the 21st century, which offers a wide range of entertainment. Young people should be educated on how to spend leisure time wisely and contribute to their own community. It is necessary to raise awareness among adolescents about the importance of getting involved in civic activism by participating in the activities of civil society organizations. Volunteering is an example of such civic engagement, as an indicator of the civil society development of the community. Through voluntary work adolescents are provided with the opportunity of personal development, self-actualization, and competence improvement as well as their contribution to the local community. Adolescents can get involved in volunteering within their educational institutions and civil society organizations. The paper shows an overview of previous research on volunteering and leisure time of adolescents in the Republic of Croatia and aims to give a deep insight into volunteering habits of Croatian adolescents, their attitudes towards volunteering, motives that affect volunteerism and the ways of spending their free time. Conclusions and an explanation of the importance of volunteerism in the modern world are presented: a culture of volunteering has a great impact on the complete personality development of adolescents; it demonstrates a wise way of spending free time among young people; it helps them acquire skills necessary for their professional growth, and the scope of interest largely depends on their career choice. Volunteering is based on solidarity and understanding others and the community, and as such is vital for civil society enrichment; therefore, it is crucial to raise awareness about the importance of promoting a volunteer culture in the free time of adolescents.