This paper makes novel claims and presents new evidence for the binarity of prosodic phrases, alignment of focused elements, and their interaction. Several authors have argued that there are binarity restrictions at the level of the prosodic phrase (e.g. Prince 1980, Ito & Mester 1992, Selkirk 2000). In this paper, I provide new support for this claim from Taiwan Mandarin (TM). I argue that prosodic phrases must be decomposed into Minor Phrases (MIPs) and Major Phrases (MAPs) (Selkirk et al. 2004), and that both levels can have minimal and maximal binarity restrictions. Crucially, MAPs must be binary in TM. Moreover, I argue – after Féry (2013) – that focused elements can require both left and right edge alignment of a constituent (in TM, a MIP). Finally, I show that requirements on binarity and focus can interact in striking ways – a binarity restriction on MAPs prevents alignment to the right edge of focused elements in specific environments.