In the first decade since the sorority's inception, the founders took steps to lay the groundwork of the sorority's foundation, including joining the Association of Education Sororities. In 1915, Tri Sigma absorbed the two remaining chapters of Sigma Delta Chi sorority. Additional collegiate chapters were established and all members met at a convention. As the sorority grew, the national nature of Tri Sigma solidified with the standardization of a ceremony for new members and the establishment of a Founder's Day to celebrate the founding of Sigma Sigma Sigma.