In 1990, the Ateneo Legal Aid Society (ALAS) was formed by law students who wanted to provide free legal aid to those who cannot afford the services of a lawyer. Clients were typically from the urban poor.

Four years later, in 1994, the student organization ALAS was placed under the administration of the Ateneo Human Rights Center (AHRC). ALAS was provided with an office space by the law school administration. The cases handled at the time were limited to labor, children, urban poor, and human rights cases.

In 2004, ALS Dean Cesar L. Villanueva removed ALAS from the administration of the AHRC and created a separate office to be known as the Ateneo Legal Services Center (ALSC). Atty. Gilbert V. Sembrano and Atty. Giovanni F. Vallente were appointed as the first Co-Directors.

In the years following, the Clinical Legal Education was made an integral part of the ALSC. A Memorandum of Agreement was entered into between the ALSC and the Public Attorney’s Office (PAO), where the ALSC student-interns would render assistance to PAO lawyers. The ALSC likewise participated in legal missions in poor communities.

In 2013, Atty. Nina Patricia Sison-Arroyo joined the ALSC as Assistant Director, and Atty. Vallente assumed the role of an adviser of the ALSC. The criteria for accepting cases was refined to give priority to cases in Makati, Mandaluyong, and San Juan. Cases outside these areas were accepted only under exceptional circumstances and depending on the availability of volunteer lawyers and students who reside in the area.

In 2014, the PAO engagement was suspended in view of the introduction of the tracking system in the ALS curriculum. Instead, a Memorandum of Agreement was entered into by the ALSC, the Ateneo Law Alumni Association, Inc., and the Humanitarian Legal Assistance Foundation for jail decongestion.

In the same year, the ALSC and the Ateneo Law Student Council mobilized about 200 students to volunteer with the Human Rights Victims Claims Board. An estimated 2,000 claimants were assisted by the ALSC student volunteers.

In 2015, the mission and identity statements of the ALSC were refined to change the targeted clients to “poor and disadvantaged” instead of limiting it to poor only. This is to expand the service to those who are not technically indigent under the Rules of Court but are unable to afford a lawyer due to circumstances.

In the same year, Atty. Axel Rupert M. Cruz assumed the position of Director of ALSC and Atty. Sison-Arroyo transitioned to being an adviser. It was also then that the ALSC announced its aspiration to be a global leader in alternative dispute resolution, and embarked on establishing a mediation practice.