For almost as long as selective dorsal rhizotomy (SDR) has existed, there has been debate surrounding which patients should be eligible to undergo the procedure. The selection criteria used to identify suitable surgical candidates have remained largely unchanged for the last three decades, despite the popularity and use of the procedure increasing. Historically, those aged between 3 and 9 years, those of GMFCS level 2 or 3, and those without evidence of dystonia were considered for SDR. In recent years, as the procedure has continued to develop, however, these parameters are expanding, with evidence to suggest a much broader cohort of patients may benefit from SDR than once thought. This chapter seeks to review current practice in patient selection for SDR, as well as the potential directions that this controversial discussion may move towards in the future.