It has aimed by this research at presenting new interpretations to diversification phenomenon and its possible effects on firm value. These interpretations are culminated by the disclosure of the distinct role of resource-based view in the study of relationship between diversification strategy and firm value. The study has conducted on a sample consisted of the largest American companies listed in Fortune 500 along with seven years period
(2005-2011). This first local attempt, which has based on panel dat--a analysis for interpreting an expected variance of firm value due to diversification strategy, may helps with a clear vision to solve the contradiction and confusion surrounded the true linkages between the two studied constructs , as a strategic objective pursued towards the intent of survival in the radical environment of 21-st century. Careful awareness conceptualization of the study's problem with its dimensions on the one hand, and trying to overcome its effects on the other hand, have led to deduct many hypotheses to explain the relationship between diversification and  firm value, which have been coincided with moderators in consistent with the resource-based theory. The statistical analysis has revealed that both direct effect and financial resources availability hypotheses were valid, which have explained the significant moderating role of a high flexibility financial resources in the relationship between unrelated diversification and firm value.