The Schneider Employees' Association (SEA) was established in 1945 after workers at the Schneider Foods plant voted to be represented by an internal employee association. At the time United Packinghouse Workers of America (UPWA) was also vying to represent the employees. Prior to the employee association being established, Schneider Foods was well known for its positive relationship with its employees and benefits including free meals, sick leave, and employee redistribution to help ensure everyone had a fair number of hours. The history of the SEA indicates that the Committee for Industrial Organizations (CIO) specifically targeted Schneider Foods for unionization because of this relationship, believing that if they could organize here where workers had an amiable relationship with their management, they would be able to organize anywhere. A group of 12 workers at Schneider Foods felt that an internal employee association would be better able to understand the needs of the workers than an outside organization and as such they drafted a proposed constitution and elected officers.

The original executive consisted of John Albrecht (president), Edwin Yanke (vice-president), Edwin Hurlbut (secretary) and Cecil James (treasurer). This employee association was sanctioned by the management and they began recruiting members. Almost one year after the SEA was established, workers at the plant voted to elect the SEA as the legal bargaining unit and the first meeting was held December 10, 1945. The first collective agreement was signed on September 23, 1946 granting employees a 12 cent per hour raise. In June of 1947 a hospital, medical and sick leave benefit plan was agreed to that covered employees as well as their families and in 1949 an employee pension plan was arranged. By 1956 there was some disagreement among employees as to whether the SEA was still the best choice, or if they should be represented by the United Packinghouse and Commercial Workers of America (UFCWA). A vote on April 4, 1956 saw the SEA continue to represent employees and negotiate a new two year agreement. Throughout the next few decades the agreement would be updated, and benefits changed, to keep in line with the changing needs of the employees, including equal pay for women workers in 1971.

During the mid 20th century there were more changes at the plant and to the agreements, including covering employees in Ayr, Wellesley, Thunder Bay, Manitoba, and Alberta. Throughout the years there was only one strike, in 1988, and relations between the employees and the company remained amiable through many changes in ownership after the Schneider family sold the company in 1997. In 2014 the Schneider Foods plant in Kitchener closed for good and the SEA ended after almost 70 years.