The Electrical Contractors Association of Ontario was founded in 1948 to serve and represent the interests of the electrical contracting industry. Over its history, ECAO has been committed to addressing the needs of the industry by providing a variety of services directly to the membership, and by making representations on behalf of the entire industry to government and industry colleagues. Its success has been due to the support and active participation of the industry.

The ECAO membership consists of bona fide electrical contractors with a contractual relationship with the International Brotherhood of Electrical Workers (IBEW). Contractors that qualify may have their dues paid through an area Electrical Contractors Association (ECA). There are presently 11 Area ECA's which are affiliated with ECAO. Contractors that do not qualify for area ECA membership may be members on an individual basis directly with ECAO. Industry product and service suppliers may join as Associate Members and are listed on the Associate Member Directory