This paper examines the informal justice and customary law, which play a very significant and essential role in resolving disputes in Afghanistan. The main and well-known form of informal justice in Afghanistan is Jirga. It is discussed that jirga as a traditional Afghan institution is meticulously bound up with the social and economic realities of daily life in Afghanistan and is deeply rooted in the history and culture of Afghan citizens. It is argued that jirga as a long-established institution does not only resolve many national, local and tribal disputes effectively and efficiently and in cost-effective ways but also acts as an influential and impressive channel of communication among the people of Afghanistan. Jirga, therefore, plays a vital part in strengthening social harmony and unity among Afghans and contributes considerably to the maintenance of social order in Afghan society. However, the effectiveness of the Jirga as a mechanism for resolving the disputes among the residents depends on the level of its perception by different parts of the Afghan people. It is believed that there is a persistent need for a Jirga to resolve many contemporary national, local, tribal and social disputes and matters in post-war Afghanistan. Furthermore, Jirga needs to be a more inclusive institution that represents both men and women and to be more sensitive to the universally accepted principles of Human Rights. Both past and current experiences show that there is reason to believe that jirga can bridge tradition with modernity.