Party activities can be traced to 1925, when party member and future General Secretary Tim Buck began shop-gate meetings and soap-box speeches at Ford. In June of 1928 the party's mouthpiece, The Worker, announced the formation of a new union - the Auto Workers' Industrial Union of the Border Cities. By the end of that same year the union had established locals in Windsor and in two other cities, claiming a combined membership of 680. By April 1929, it had launched its own journal: The Auto Workers' Life.

This success was the result of efforts by the Workers' Unity League, which was built around a faithful and militant nucleus of party members who proficiently chaired meetings, gave speeches, printed pamphlets and organized picket lines. The league was less adept, however, at detecting the corporate spies that retained the posts of the president and vice-president of the union's Windsor local, and whose reports - passed on to Ford and Chrysler management - led to the dismissal of twenty activists in April of 1929. An inability to protect its members from employer reprisals coupled with the stockmarket crash of October spelled the end of the Auto Workers' Industrial Union.

During the depression of the 1930s the Communist party of Canada maintained its presence in the community and its contact with the masses. In 1930 it founded the Unemployed Worker's Association of the Border Cities, which addressed issues like relief payments and evictions. Party meetings were even held in East Windsor City Hall, where three Communist councillors held seats during 1933 and 1934. May Day parades marched to City Hall Square and, until they were declared illegal, party rallies were held in Lanspeary Park. R.C.M.P. security bulletins indicate that at least 1000 people attended the seventeenth anniversary celebration of the Russian Revolution when it was held in November of 1934 at the Empire Theatre.

Party members doggedly, but with more discretion, continued their organizing activity. By 1933 nearly a hundred unionists were spread across fourteen shop groups in eight local plants and by 1934 strikes were carried out at Auto Specialties and Canadian Motor Lamp. In 1935, when Moscow called for a "united front movement against fascism and against other imperialist war" and directed the Workers' Unity League to disband, league members began organizing for the UAW.

When five workers at Kelsey Wheel were dismissed in December of 1936 for UAW organizing activity, Communist party members acted quickly. A meeting was called at which thirty-eight Kelsey Wheel workers enrolled in the union, and were soon chartered as Canada's first UAW local-Local 195. Shortly thereafter Canada witnessed its first sit-down strike. The strike was not wholly successful but the local remained intact and continued to grow largely due to the efforts of party members. By May of 1937, two-thousand auto workers had joined Local 195.

The executive of Local 195 was largely Communist during W.W.II, but it retained the loyalty of its predominantly non-Communist members by the zeal and commitment it had demonstrated over the years to the cause of unionization. With the conclusion of the war, however, a "house cleaning" was organized and a frenzy of anti-Communist sentiment swept the Communist executive out of power.