This chapter provides a synthesis of some of the useful prison policies discussed throughout this volume. The sources of useful versus harmful policies in addition to the implications of the latter are discussed. Perhaps the most common source of harmful policies has been heavier emphases placed on punishment by politicians and court actors who are further removed from the prison experience. Common denominators of policies that have generally improved the welfare of prisoners and/or prison staff, on the other hand, include grounding in an increasingly humanitarian view of offenders, a growing awareness of both short- and long-term adverse effects of incarceration on offenders and the general population, greater reliance on empirically based strategies, and interagency collaborations to ensure long-term solutions while minimizing unanticipated ill effects. The greatest obstacles to overcoming harmful policies are also reviewed, highlighting the importance of cumulative knowledge and ongoing empirical research on best practices.