Abstract
Through Tanzania's National Sanitation Campaign, we study the effectiveness of two common elements of behavior change campaigns: endorsements from celebrities and testimonials. Using four experiments in Tanzania in early 2021 as part of the national campaign, we find that including endorsements and testimonials in text messages sent to individuals significantly increases self-reported hygiene behavior. These results mask important heterogeneity based on the source of endorsement or framing of the testimonial and provide insights into cost-effective approaches for changing behavior at scale.