Most users find security-informed decisions hard to make while utilizing web sites for social networking, online banking, or shopping. In order to solve security problems, it is critical that we understand how human factors influence users’ trust on web sites and users’ decisions involving computer security related risk. We propose an integrative model of human factors on decisions involving online security risk. The model will provide a comprehensive view of the impact of the situation and personal factors on trust, perceived security risk and web site functionality from both internal and external perspectives. The proposed model will extend existing theories by studying the human factors in terms of internal intrinsic traits such as personality, culture, risk beliefs and extrinsic factors such as experience and familiarity. Similarly it will study internal situation factors such as website performance and utility, and external situation factors such as context.