Accountability is used often in describing computer-security mechanisms that complement preventive security, but it lacks a precise, agreed-upon definition.  Here, we argue for the need for accountability in computing in a variety of settings, categorize some of the many ways in which this term is used, and propose a punishment-focused view of "accountability."  We formalize our view in a utility-theoretic way and then use this to reason about accountability in computing systems.  We also survey mechanisms providing various senses of accountability as well as other approaches to reasoning about accountability-related properties. 

This is joint work with Joan Feigenbaum and Aaron Jaggard.