In tandem with party building, de los Reyes also set about organizing a workers' movement in the Philippines. In 1902, Hermenegildo Cruz and other members of the Carmelo and Bauermann publishing house approached de los Reyes to seek advice in forming a cooperative store for rice and other staples. The "Union Democratica de Litografos, Impresores, Encuadernadores y Otros Obreros" was thus formed on February 2, 1902, which came to be known as the "Union Obrera Democratica". De los Reyes was its first president.