environment, and creating a sense of collective shame and disgust around it. The approach has been adopted in 58 countries around the globe, including in South Asia (e.g., Afghanistan, Bangladesh, India, Pakistan, Nepal); East Asia and the Pacific (e.g., Cambodia, Indonesia, the Philippines, Vietnam); East and Southern Africa (e.g., Ethiopia, Kenya, Mozambique, Uganda, Tanzania); West and Central Africa (e.g., Benin, Burkina Faso, Cameroon, Ghana, Mali, Nigeria); and Latin America and the Caribbean (e.g., Bolivia, Guatemala, Haiti) (Institute of Development Studies 2018). Depending on local conditions and policy priorities, CLTS has been combined with supply-side interventions and/or subsidies for the construction of household toilets. Supply-side interventions facilitate the availability of raw materials and trained masons in CLTS communities, whereas subsidies mostly target poor households without the means to finance the costs of construction.

Though CLTS has been widely adopted in developing countries worldwide, empirical evidence of its effectiveness is limited. While the available literature indicates that CLTS has been successful in promoting toilet ownership and reducing open defecation (Pattanayak et al. 2009; Patil et al. 2014; Borja-Vega 2014; Godfrey et al. 2014; Guiteras, Levinsohn, and Mobarak 2015; Dickinson et al. 2015; Pickering et al. 2015; Gertler et al. 2015; Crocker et al. 2016), the size of the effect varies widely within and across countries depending on preexisting local conditions and the nature and intensity of the interventions.

One multicountry, cluster-randomized study that compared the effectiveness of CLTS interventions in India, Indonesia, Mali, and Tanzania (Gertler et al. 2015) observed that interventions differed across countries. A stand-alone CLTS intervention (without complementary efforts) was implemented in Mali with monthly follow-ups for one year. In India, there was no follow-up after CLTS triggering, but a subsidy was made available to poor households to construct toilets. In Indonesia and Tanzania, there was one follow-up after triggering, and no subsidy. Moreover, except in Mali, the CLTS interventions were accompanied by supply-side interventions. The study finds that access to toilets expanded in beneficiary communities by 39 percentage points in Mali, 23.4 percentage points in India, 13.4 percentage points in Tanzania, and 7.6 percentage points in Indonesia. Except for Indonesia, where improved access resulted from a mix of new construction and the extension of shared facilities, the increase in toilet coverage came through the construction of private toilets. Mali, where a pure CLTS approach was implemented, registered the greatest reduction in open defecation rates. Open defecation rates fell by 33 percentage points in Mali, 13 percentage points in Tanzania, and less than 10 percentage points in India and Indonesia. Except in Mali, which saw a reduction of 21 percentage points in open defecation rates among households with toilets, no significant effect was found among this group (Gertler et al. 2015). The results of this study highlight the importance of community mobilization and repeated follow-ups in CLTS interventions. The results also indicate that while subsidies work to expand toilet access, they do not lead to a proportionate decline in open defecation, and that behavior 8