In everyday life we perform several activities in our periphery of attention. For example, we are aware of what the weather is like and we can wash our hands without actively thinking about it. Though computing technology is becoming increasingly present in our everyday routines, interactions with these technologies usually require focused attention. Inspired by our interactions in the physical world, this thesis explores the concept of peripheral interaction: interaction with technology that takes place outside the focus of attention. We believe that this direction may support interactive devices to better blend into our everyday routines. We explore peripheral interaction by observing how everyday activities take place in the periphery and by developing and deploying a number of physical peripheral interaction designs. We conclude with a set of considerations for facilitating peripheral interaction. With this work, we hope to contribute to interaction design research and practice by providing insights in how human attention abilities can be leveraged in interaction design