Over the past decade, the use of artificial intelligence (AI) to solve international development problems has gained momentum, including at USAID. With increasing availability of digital data, computing, and research, AI has been deployed across various sectors, including healthcare, agriculture, and education, promising greater efficiency and insights, and a novel way to address systemic problems. That trend in AI applications is predicted to only increase in the coming years. However, AI systems come with risks and unique challenges that can harm the most vulnerable -- particularly for developing countries and in international development. This has led to growing concerns about using AI responsibly. Just as we continue to learn about the awesome power of these technologies, there is a growing need to pause and look back at what has been done in order to shape and inform what is yet to come. These case studies do just that -- examining a few of USAID's AI projects to share lessons learned and demonstrate how we can continue to adopt AI tools responsibly.