This dissertation examines the Proliferation and Misuse of Small Arms and Light Weapons under the ECOWAS Legal regime taking Nigeria as a case study. The objective of this dissertation it to find out why small arms and light weapons have continued to proliferate in Nigeria despite being a signatory to the ECOWAS Legal Regime, in this case, the ECOWAS Convention on Small Arms and Light Weapons and Other Related Materials. Using Doctrinal Methodology, the dissertation shows that Small Arms and Light Weapons proliferation and misuse has increased criminality, youth violence, hostage taking, militancy, community crises, oil bunkering and insurgency. More so, it further asserts that their wide availability fuels ethno/religious conflict, political instability and has direct influence on the escalation and sustenance of peace, insecurity and development.This dissertation examines the sources of small arms and light weapons, the motivational forces behind the proliferation and Federal Government initiatives to curb this menace in Nigeria. It also focuses on the legal regime on small arms as they concern the control of small arms proliferation in Nigeria and argues that the National Law in place is out-dated and inadequate to curtail and impede the proliferation and misuse of SALW. It further argues that though the extant ECOWAS legal regime is robust enough to support any sustainable progress in this area, however, non-compliance by member States and particularly Nigeria to harmonise their laws with the provisions of the ECOWAS Convention certainly lives much to be desired.Findings revealed that the inability of the Nigeria government and the law enforcement agencies to check the supply and the demand factors of the proliferation of SALW in Nigeria has heightened and worsened the security situations in the country. To this extent, the dissertation recommended amongst others, that there should be significant changes in the National legislation harmonizing same with the ECOWAS Convention because of the minimum standard requirement in article 21 of the Convention while dealing with the demand factors of SALW that heightens the proliferation of SALW by partnering with the private sector to undertake an aggressive job creation programme for Nigeria‘s teeming and idle youths.