The legal standards for reviewing claims of ineffective assistance of counsel at sentencing are underdeveloped. In other contexts, defendants seeking to prove ineffective assistance must demonstrate that counsel's performance fell below appropriate professional standards and that there is a reasonable probability that, but for counsel's deficient performance, the result of the proceeding would have been different. The doctrinal uncertainty whether that standard applies to sentencing proceedings in non-capital cases, coupled with worries that ineffective assistance at sentencing claims will result in a flood of litigation, has led some courts to require defendants to satisfy stricter prejudice standards in discretionary non-capital sentencing regimes. This Article analyzes the ineffective assistance jurisprudence and concludes that the sufficiency of counsel's performance is largely evaluated against a backdrop of relevant substantive law. The substantive law of non-capital sentencing is not welldeveloped, which may explain the underdeveloped state of ineffective assistance at sentencing standards. Drawing on several recent ineffective assistance cases in the death penalty context, this Article identifies legal principles and practices that may assist in making the legal assessments necessary to analyze ineffective assistance at sentencing claims. These principles and practices may provide a sufficient legal framework to render unnecessary the crude manipulation of the prejudice showing that some courts have employed.