ABSTRACT Retained Foreign Objects (RFOs) are one of the most well recognized and persistent patient safety problems, affecting between 3000 and 50,000 patients per year, with an 80% morbidity rate, The primary defense is the manual counting of items that enter and leave the surgical field (the “surgical count”), which can be unreliable, while technologies, policies and training still leave many potential opportunities for failure. We propose a Patient Safety Learning Lab that will explore the causes of and solutions to RFOs using a systems engineering approach. Our initial systems models will drive improved understanding of factors that influence successful and unsuccessful counting. Laboratory experiments in count grouping, including time pressures, distractors, and the role of technology will define and build an evidence for optimal count strategies. It will also be possible to identify multiple opportunities to enhance the perioperative count process prior to the commencement of the procedure; and the discovery of lost items in the case of a discrepant count. Finally, as RFO performance is affected by organizational work contexts, we will explore opportunities to enhance teamwork, and organizational learning processes post-event. This work will initiate the most fundamental reappraisal of the causes of and solutions to RFOs for more than 20 years.