Arising from the recent shift in the attitude of main contractors to subcontract procurement in some of the developing countries of the world, this study presents the findings of the importance of factors influencing the choice of subcontractors by the clients and contractors. With a focus on three commercial nerve centres of Nigeria (Lagos, Abuja and Port Harcourt), the study presents the findings of a survey of construction clients/contractors and rank the factors they consider in the selection of suitable subcontractors for project execution. The results of the relative index ranking technique indicate that five most important factors are: subcontractors’ past experience in terms of size and type of projects completed; subcontractors’ management resource in terms of formal and informal training; other related issues in terms of nature of contract and time of the year (weather), past relationships with the clients/contractors (past performance), and project facilitation in terms on labour/plant resources. It is concluded that greatest premiums should be attached to some of these factors for improved construction sustainability.