The society is organised in three officially declared regions in southern and central India: Ujjain in Madhya Pradesh, Mandya in Karnataka and Sangli in Maharashtra; M.S.T.
The 8th Ordinary General Assembly of the Missionary Society of St Thomas the Apostle began on 14 May 2008 at its Central House, Melampara, Bharananganam.
In the words of Cardinal Lourdusamy, it was in 1962 "that the Missionary Society of St Thomas the Apostle began to take shape in the vision of late Mar Sebastian Vayalil, then Bishop of Palai".
[3] During the ad limina visit of 1960 Vayalil met Pope John XXIII and apprised him of the plan to begin an association to canalize the vocations of the Syro-Malabar Church.
In the 1950s there was a sudden boost in the number of young men of the Syro Malabar Church going to do missionary work in India and abroad.
It was in this background that Sebastian Vayalil while preparing for the ad limina visit of 1960 came across the idea of beginning an association of priests of the Syro-Malabar Church to canalize the missionary vocations.
Kurian Vanchipurackal and John Perumattam were entrusted with the task of preparing the report of the diocese to be presented to the Holy See.
The report clearly was an eye opener to the bishop to see that many young men of the diocese had to change their rite to become missionaries.
It was the immediate reason why the bishop began to think about forming a missionary association and he included this project also in the ad limina report.
While presenting his report to Pope John XXIII, the bishop informed him of the plan to begin an association for mission work.
Welcoming the idea, the pope asked the bishop to consult with the experts in the Roman Congregation for the Eastern Churches and missionary Propaganda Fide.
Thus the idea about the missionary association got more clear with the discussions held at Rome Coming back from the ad limina visit, Mar Vayalil proposed in an official meeting of the Syro-Malabar Bishop's Conference the plan for a missionary society for the Church: "It should be a common society of the whole Malabar church to be erected by the hierarchy and placed under it".
The Bishop informed the members of the commission he had to start and organize the missionary institute as a Pious Union of the diocesan clergy for mission work.
The Missionary Society of St Thomas the apostle was formally erected and its Constitution was promulgated on 22 February 1968 by Bishop Sebastian Vayalil in a function presided over by Cardinal Maxmilian de Furstenburg.
By the special faculty obtained from the Holy See, Sebastian Vayalil, on 16 July 1968, appointed John Perumattam the first Director General of the society.
Perumattam tendered resignation as he became the Exarch of Ujjain, Joseph Maliparampil was nominated and appointed as the Director General by the Bishop of Palai.
Deepti Bhavan, which was constructed under the supervision of Sebastian Pottannany according to the plan drawn by Larry Baker, was inaugurated on 30 December 1972 by Cardinal Joseph Parekkattil.
But on March 11, when all gathered at Bishop's House (First General Assembly), contrary to all calculations, it was decided to start the Minor Seminary that year itself at Ampara and to erect building ad hoc borrowing the necessary fund from any source".
[7] Thus Deepti College, the Minor Seminary of MST, officially came into being on 31 August 1969 with Sebastian Thuruthel as Rector and Joseph Thaiparampil as Spiritual Father.
Right from the beginning of the attempts to form a missionary institute of the Syro-Malabar Church there is one idea running through: the Sons of the Christians of St Thomas must be able to do evangelization outside Kerala in their own rite.