ix Abstract Source separation of municipal solid waste is a requisite fora sustainable waste management practice. Concerned residents of Lagos, the fourth largest city in the world, during the period of this study had been alarmed by the backlog of uncollected MSW, which now spills over into public roads, drains and street corners thus creating the trepidation of an epidemic. This study assessed the knowledge level of residential households on the source separation of HSW and their understanding of the waste hierarchy guideline. Concurrently, an investigation of the waste management authority’s requirement for source separation was also carried out. Data was collected through a questionnaire survey administered on 200 residential units (n = 200) using the systematic random sampling method at intervals of 10 housing units apart while one questionnaire was administered on the waste management authority. Analysis was carried out with Microsoft Excel with the aid of descriptive statistical tools. The results showed that 73.5% of the households do not know about source separation while 57.5% have no knowledge of the waste hierarchy guideline. Reference to the Perceived Behavioural Control construct of the Theory of Planned Behaviour indicated that 65% are strongly willing to learn the modus operandi of source separation while the Subjective Norm construct portrayed that 87.5% would be encouraged to separate waste from source if they see others in their neighbourhood do same. The study therefore recommends that increased public awareness that must involve traders in the neighbourhood should be tailored inline with a novel approach as grassroot participation by way of town hall meetings in collaboration with CDAs and LCDAs, where public demonstration of how the process of source separation and waste reduction practices are taught by environmental educators.