Understanding human behavior is generally a difficult task because of the complexity of the individual (or the group of individuals) that is subjected to intertwined factors, forces, values, and other motivational resources that are influencing behavior. A qualitative model of the individual was developed to account for the factors and forces exerted on the individual and the individual's goals. Personal behavior was further modeled by a vector with a magnitude and a direction. The magnitude depends on factors and forces that may be unleveraged or leveraged. The direction of the behavior vector represents the goals of the individual. The behavior model was extended to a group of individuals by considering a group vector. The role of past experience and resources supporting and influencing the indivual and the group were identified and discussed. Decision processes for the individual and the group were developed since it is through decisions that behavior is developed and adopted. The model also includes immutable factors to guide the individual toward a task-oriented or relationship-oriented human behavior. An error process was also developed to identify and correct errors so that the decisions taken are accurate, complete, and uptodate. Several illustrative applications of the human behavior model are presented and discussed. These applications relate to the individual and the group with specific goals and in particular situations.