Against those cynical of the desirability or possibility of meaningful PIs in drug enforcement, the author argues the effort is justified, not only in the interests of the manageability and accountability of drug enforcement agencies but also more broadly as an aspect of transparency in policy-making and of the balancing of competing claims in a democratic society. Drawing particularly on sources in the United Kingdom, the author illustrates the urgency of the demand for PIs; explores political, conceptual, and technical difficulties in their development; proposes a broad framework within which they can be conceptualized; and advocates vigorous research engagement with issues related to PIs. The author notes challenges include improving the interpretability of established measures such as drug seizures and drug arrests, evaluating new orthodoxies such as disruption, and developing measures of the impacts of interventions and policies in terms of market-related harms and enforcement-related harms. Practical issues associated with performance management and drug enforcement are examined, including the development of independent, audit-type checks of PIs that rely on the judgment of drug enforcement officers. The author urges consideration of the merits of a move to multi-year reporting and accounting periods in order to concentrate interpretative resources on larger and more robust data sets and reduce the presentational effort currently districting senior drug enforcement managers, policy-makers, and researchers. 23 references, 6 notes, and 1 figure