According to the TWAS Statutes, the Academy's membership consists of the following categories:
- Fellows : elected from scientists who are citizens of developing countries and have attained the highest international standards, and
- Associate Fellows :elected from scientists who are citizens of developed countries who either have their origin in developing countries or who have distinguished themselves in the context of Third World science and who have made outstanding contributions to their respective fields of science.
Election procedure:The Statutes further state that the nomination of a candidate for election must be made in writing on a form called "Certificates of Election"  signed by a Fellow or an Associate Fellow of the Academy. Completed certificates are evaluated by a Membership Advisory Committee, and then submitted to the TWAS Council. After reviewing the comments and recommendations made by the Advisory Committee, the Council recommends a final list of candidates for election. The names of the candidates selected are then communicated to the Fellows and Associate Fellows attending the General Meeting. Candidates receiving a favorable vote by the majority of Fellows and Associate Fellows present are elected.
Blank "Certificates of Election" are available only upon request and are sent to TWAS members only. They are not sent to non-members.