Interactive playgrounds are technology-enhanced installations that aim to provide rich game experiences for children by combining the benefits of traditional playgrounds with those of digital games. These game experiences could be attained by addressing three design considerations: context-awareness, adaptability, and personalization. The authors propose using social signal processing (SSP) to enhance current interactive playgrounds to meet these criteria. This article surveys how SSP techniques can help playgrounds automatically sense and interpret children's social interactions, adapt game mechanics to induce targeted social behavior, and learn from the sensed behavior to meet players expectations and desires.