A developing country like Nigeria continuously needs the impact of entrepreneurs to contribute to her economic growth and development. The construction industry, known to be an important sector in any nation and one of the services sectors that has a great influence on a country’s economy has a wide scope and is vastly diversified. The vast nature of the industry has posed a wide range of business opportunities for entrepreneurship, allowing startups of small and medium scale enterprises (SME) in the sector. However, despite the diverse opportunities in the sector, many of these new and existing SME construction firms in Nigeria have been forced to pack up as a result of high rate of entrepreneurial failure. This paper therefore highlights entrepreneurial capacities of the SME Nigerian construction firms as an important factor for their sustainability, thus assessed those important entrepreneurial capacities that are required of SME construction firms for continuous and effective existence. The study utilized both secondary data from past works and primary data sourced by administering a structured questionnaire to construction professional of SME construction firms located across Lagos state. A total of 100 questionnaires were distributed and 90 were returned. Collected data were analyzed using percentage distribution and Relative Importance Index (RII) for proper data presentation. This study showed that majority of the respondents (80%) agreed that entrepreneurial capacity in SME construction firms is significant for sustainability. Results also showed that innovativeness, financial management, ability to exploit new opportunities and strategic planning are high in importance as entrepreneurial capacities required by SME construction firms in Nigeria to sustain their existence. Other capacities highlighted include time management, human resource management, business ethics, and communication etc.