The advance in User Created Contents (UCCs) web sites like YouTube changed the role of Internet users from contents receivers to contents creators; a role which requires more pro-active user behaviour. However, the literature on user behaviour in information technology lacks theories that explain the pro-active user behaviour of producing and sharing UCCs with others on the Internet. This paper aims to reveal the major attributes of Internet users that have a positive impact on the intention to produce UCCs on the Internet. Extant related theories are reviewed to extract major factors of Internet users that lead to the production of UCCs. A questionnaire survey is administrated to 400 sampled respondents in South Korea to test the relationships among the identified factors. The results show that playfulness, self-expressiveness/sharing intention, innovativeness, computing skills and reward have a positive impact on the intention to produce UCCs. In particular, innovativeness turned out to have the biggest impact, while social participation is not a significant factor. Mediator variables such as age, gender and types of UCC also turned out to be playing a role in the causal relationships among the factors and the intention to produce UCCs. A model pertaining to the intention to produce UCCs online is developed and tested. The academic and practical implications of the study are also discussed in details.