BACKGROUND: Research often suffers from overspecialization, a practice nurtured in academia and reinforced by funders. Indeed, investigators in household air pollution (HAP) and water, sanitation and hygiene (WaSH), working in poor parts of the world, rarely interact despite having similar training and using similar methods to evaluate interventions in the same vulnerable populations. Disappointing results from recent trials of improved cookstoves and traditional approaches to WaSH suggest the need for alternative approaches. OBJECTIVES: We argue that bringing these two areas together would improve the effectiveness and efficiency of interventions to reduce the massive disease burden associated with HAP and poor WaSH, including pneumonia and diarrhea, the leading killers of young children in low-income countries. RESULTS: HAP and WaSH face similar challenges in designing, implementing, and securing the sustained and exclusive use of scalable interventions such as clean fuel and water. DISCUSSION: Research can advance greater coordination of these areas by demonstrating their interactions and wider impacts on well-being as well as the potential for programmatic synergies. Integrated solutions to clean households and communities can benefit from the contribution in multiple disciplines, including economics and policy analysis; business and finance; engineering and technology; lab sciences, environmental health, and biomedical sciences; and behavioral and implementation sciences. CONCLUSION: There are compelling reasons to overcome the artificial and unproductive segregation of HAP and WaSH. Researchers should encourage integration by expanding the scope of their collaborations and projects. Policy makers, funders, and implementers can help by supporting comprehensive solutions, encouraging innovation, and requiring rigorous evaluations of their effects. https://doi.org/10.1289/EHP4752.