Diarrhea and growth faltering in early childhood reduce survival and impair neurodevelopment. This paper assesses whether a national program in the Democratic Republic of Congo reduced diarrhea and stunting and strengthened local water and sanitation institutions. The program combined (i) funds for latrine and water upgrades, (ii) institutional strengthening activities, and (iii) behavior change campaigns. In 2018, the program was randomly assigned, after stratifying by province and cluster size, with 50 intervention and 71 control clusters. In 2022-23, 3,283 households were interviewed, at a median of 3.6 years post-intervention. The intervention had no effect on diarrhea and no effect on length-for-age Z-scores in children. Villages in the intervention group had a 0.40 higher score on the water, sanitation, and hygiene institutions index. The percentage of villages in the intervention group with an active water, sanitation, and hygiene (or just water) committee was 21 percentage points higher than the control group. Households in the intervention group were 24 percentage points more likely to report using an improved water source, 18 percentage points more likely to report using an improved sanitation facility, and reported more positive perceptions of water governance. The Democratic Republic of Congo's national rural water, sanitation, and hygiene program increased access to improved water and sanitation infrastructure, and created new water, sanitation, and hygiene institutions, all of which persisted for more than three years. However, these effects were not sufficient to reduce diarrhea or growth faltering.