The lessons learned from the fatal accidents that occurred in the beginning of the century highlighted concerns and issues related to staffing in Air Traffic Control (ATC) units, i.e. Single Person Operations (SPO), staffing during all operations, and position handover. In the Strategic Safety Action Plan (SSAP) developed by EUROCONTROL as a response to the Linate and Ãœberlingen accidents, a specific work package was identified to address issues on adequate levels of staffing, which has led to this study on selected safety issues for staffing ATC Operations. The referred work package has been approved by the Provisional Council to be continued and fully delivered under the European Safety Programme for Air Traffic Management (ATM) under its Activity Field 5, ˜Safety Management Enhancement™. The purpose of this study was to review practices and trends for the staffing in ATC Operations that focused on the following safety critical issues: 1) Staffing in degraded systems operations. 2) Staffing during workload extremes. 3) Staffing during night work. 4) Single Person Operations (SPO). 5) Position handover. 6) On-the-Job Training (OJT).