It is apparent that understanding the group process and outcome literature is complex. However interestingly, despite the wealth of evidence showing individual self-esteem to be a good predictor of treatment outcome, prior research in the group treatment area does not appear to have taken into account the extent to which outcomes may be affected by self-esteem levels of other group members. In addition, no study has investigated the effect on outcome when self-esteem of the individual varies relative to the self-esteem of other group members. In his early work, Festinger (1954) proposed social comparison theory (SCT), which assumes that when people are unsure of their skills and capabilities, they tend to compare to others as part of a self-evaluative process. The direction of the comparison can be either upwards (comparing to a more fortunate group) or downwards(comparison with a less fortunate group). Wills (1981) claimed that when under threat, individuals tend to engage in downward social comparison. The comparison with less fortunate individuals,Wills claimed, enables people engaging in such comparisons to feel better about themselves.