Most current mobile technologies require on-screen operations for interacting with devices' visual contents. However, as a trade-off for mobility, screens usually provide limited space for interactions. To address this problem, I explore Body-Centric Interaction (BCI) -- a design theme that extends a mobile device's interaction space from screen space to body space. My research methodology follows several steps. First, I use a generative bottom-up method -- sketches and proof of concept implementations -- to frame the breadth of the design space. Second, I populate the space with related work, which also unifies what has been done. Third -- which is work in progress -- I explore the depth of promising BCI methods, with the goal of developing, refining and testing particular mobile interaction techniques.