Sensing technologies that provide continuous, real-time information about teachers' and students' individual experiences are increasingly being applied to classroom-based research. Sensing technologies provide a possible alternative to costly and time-intensive in-person or hand-coded observations and have the potential to increase our present understanding of the vastly different experiences students within the same classroom often have. The goal of the present article is to provide an overview of sensing technologies, an explanation of how these technologies can be applied in early childhood classroom-based research, and examples of existing studies that have successfully implemented sensing technologies in the classroom environment.