Former Speaker of the Rajasthan Legislative Assembly Sumitra Singh on Thursday joined the Congress here. She joined the Congress in the presence of AICC general secretary Avinash Pande, PCC chief Sachin Pilot, former chief minister of the state Ashok Gehlot at the PCC headquarters here. Singh, who has been the member of the legislative assembly for nine terms, was the speaker during the first tenure of Chief Minister Vasundhara Raje.