Costilla worked for the employment services office in Toledo for thirty-three years, beginning as a bilingual interviewer and retiring as a regional supervisor. Through her work, and as a volunteer for Catholic Charities Migrant Ministries, she helped migrant farmworkers find employment and access social services. Costilla also served as co-president of Toledoans United for Social Action, a non-profit that works with local churches to organize community actions related to
anti-violence and
substance abuse prevention. Her advocacy work also includes volunteering for the
Lucas County Democratic Party and organizing fundraisers for scholarships at Latino community festivals. Costilla is a leader in the
toledano community, people of Mexican descent living in
Toledo, Ohio. She coauthored a study about differing views of assimilation and Mexican identity among
toledanos. ==Awards and legacy==