The history of St. Sebastian’s College can be traced beyond 160 years. However, the recorded history counts from the year 1926 after the De la Salle Brothers took over the administration of the school. Only five years later, the inaugural meeting of the Old Boys’ Association was held on 14th July 1931 with Rev Bro. Bonaventure Idus as the President, Mr. Peter. B. Dias as Hony. Secretary and Rev. Bro Joseph Charles as the Hony. Treasurer with a committee to manage the affairs of the Association.

Over a period of 55 years the Administrator of the school functioned as Ex-Officio President, while the Hony. Secretary functioned as The Chief Executive Officer of the OBA.

It is a well-known fact that the OBA played the key role in the action, along with teachers, parents & well-wishers during the school take over in 1960 which eventually preserved the status of the College as a private non fee levying school. The challenges that the administration had to face were so enormous and brought hardships specially in raising funds for financing the needs of the school. In the year 1974The De La Salle Brothers felt that it is not feasible to continue the school any further as a Private Non fee levying school with the constrains they were facing especially in meeting the financial commitments. At this crucial stage the OBA rose to the occasion and accepted the challenge by forming a fully-fledged Welfare Society to raise & manage the entire finances of the school. This arrangement continued till the year 1978, when the then government agreed to extend the financial support for a selected category of teachers. It is noteworthy to mention the excellent leadership & effort made by the Old Boys under the leadership of late Mr. Eardley Perera PC, with the unstinted support of Mr. Peter Perera, Mr. Eugene de Siva and Mr. Julian Fernando.

Due to controversial conditions prevailed in 1986, the OBA decided to elect a Lay President. A long standing much respected member of the O.B.A and the person who pioneered the first Old Boy Batch “The 33 Circle”, Late Mr. Eugene de Silva was elected as the First Lay President. With the advent of the Director who assumed duties in 1987, The Presidency was again reverted back to the earlier practice and the post was held by the Directors in succession until the year 2001.From the year 2001 the practice was changed and the Presidency continued to be with lay members.

In the year 1991 the De la Salle Brothers introduced the concept of participatory management with the formation of a Board of Governors and a School Development Society with Old Boys as the Chairman and President respectively. Over a period of ten years the Old Boys played a vital role in fund raising projects and the financial management in the school. The benefits derived by the school under this concept were not only in improving financial resources but also attracting human resources with special aptitudes towards the school .The OBA was successful in formation of overseas branches in countries such as U.K ,Australia, Canada & U.A.E. The concept of formation of Old Boys Batches too commenced.

The 75th Jubilee of the College was celebrated in the year 2001 in a most fitting manner and the great gift given to the students by the OBA in commemoration of the event was the Auditorium.

Another turning point in the college arose in April 2003. On a directive by the Archbishop of Colombo, who is the proprietor of the school, the administration of the school was handed over to the Reverend Priests in the Colombo Archdiocese and Rev. Fr. Bonnie Fernandopulle was appointed as the First Rector of the school. This was a beginning of a Golden Era of the College.Fr Rector secured the fullest support of the Old Boys, Teachers, Parents, Well Wishers and the students and moved to work on a Master Plan for the improvement of the standards of the College to be completed within a period of ten years. Thanks to the God Almighty and the untiring efforts & leadership of Rev.Fr Rector, most of the projects planned in the said Master Plan were successfully completed within the first six years.

The College was brought to the standards comparable with all leading Colombo schools not only in the sphere of education but also in sports, discipline and in other extra- curricular activities. The old Boys were relieved in the responsibility of fund raising activities to a certain extent as Fr Rector spearheaded that responsibility as well. On the request of the Fr Rector the OBA played a major role in collecting funds for the swimming pool, chapel Project & for establishing the school computer center. The fast developments taking place in almost in every sphere under the guidance of the Fr .Rector was an eye opener and an encouragement for many old boys to rally round the school and the activities of the old boy’s batches in assisting the College were very prominent and that enthusiasm promoted formation of more and more batches.

It is appropriate to put on record the following benevolent funds created through the involvement of the OBA. The H.W. Massinor Trust Fund, formed by a German Philanthropist through the bequeath of his Last Will provides financial assistance to the students whose parents are unable to meet the school levies. Late Mr. Eardly Perera Memorial Fund formed through the contributions made by the Family & well-wishers of Late Mr. Perera assists in providing scholarship to outstanding students of the College. Through a generous donation by Mr. Kumar De Silva in memory of his late father a Trust has been formed as an Old Boys Welfare Fund.
With the intention of revamping the activities of the OBA, constitutional reforms have been introduced to accommodate more and more young members to the General Committee of the OBA. Currently the committee consists of 90 members including a representative from each recognized batch of Old Boys.

The OBA activities too have been broad based. Originally they were restricted only for the organization of the Big Match & the College Sports Meet .Now the OBA calendar consists of Stag Night, Beach Party, Family Get Together, Sports Day, Annual Dinner Dance and the Christmas Get Together. In addition to these annual events projects such as Back to School, Teachers Day and Medical Health Camp were conducted with the support of the Old Boys batches. The Annual Dinner Dance became the main fund raiser for the association and became one of the most colourful events in the OBA calendar. It is pertinent to mention that the College Annual Dinner Dance has been held for 12 consecutive years with positive improvements every year, as a result of Old Boys, Young & Old blending together well, in the organization of same. The Dance has now become a much sought after Event.

The Old Boys Association with a current membership of well over 2000 take pride in the fact that the objectives of the association as spelled out in the Constitution have been more than realized over the last 85 long years.