Rekha Mammen joined the Rural Campus of the Tata Institute of Social Sciences as a Social Worker in 1988 on graduating with a Masters in Social Work with specialization in Rural and Urban Community Development.

At the Rural Campus she was involved in rural development work that focused on local resource development through land and water management projects, local resource-based self help initiatives and organization of farmers, labourers, women and other marginalized groups around issues related to land rights, water, wages, corruption, literacy and education. She was also involved in various research and training initiatives including the external evaluation of the Total Literacy Campaign in Latur District, Maharashtra and a Joint Action Group survey of the earthquake affected villages of Latur and Osmanabad districts. She also assisted the Collector, Latur at that time in the initial efforts to coordinate NGO relief work in the district, and was subsequently appointed Project Associate of the Consultancy for Community Participation and Monitoring Community Participation in the Earthquake Affected Areas of the two affected districts.

She joined the research Unit for Rural Studies, TISS in 1995 after obtaining a Diploma in Rural Policies and Project Planning from the Institute of Social Studies, The Hague, Netherlands. She was involved in teaching various basic courses in the Social Work Masters Programme as well as some of the certificate programmes. She continued her association with the Rural Campus and was over time responsible for the coordination of the work of the Rural Campus and facilitated liaison between the Mumbai and Tuljapur campuses. She was also Convenor of the Curriculum Development Committee that developed the Bachelor's programme in Social Work with specialization in Rural Development. 

She joined the Centre for Community Organisation and Development Practice in 2005 and has completed her Ph.D. on 'Community, Nature and Interventions: Emerging Landscapes in the Peri-Urban Region of the Mumbai Metropolitan Region'. Her primary engagements have been with community participation, land-water conservation projects and community-environment relationships. She is currently associated with a network of informal workers in Raigad district and a citizen's forum for public transport in the city of Mumbai, with the aim of understanding the outcomes of development activities on the poor in both urban and rural spaces.