This festschrift was written in honor of Andrew William (Bill) Roscoe on the occasion of his 60th birthday, and features tributes by Sir Tony Hoare, Stephen Brookes, and Michael Wooldridge. Bill Roscoe is an international authority in process algebra, and has been the driving force behind the development of the FDR refinement checker for CSP. He is also world renowned for his pioneering work in analyzing security protocols, modeling information flow, human-interactive security, and much more. Many of these areas are reflected in the 15 invited research articles in this festschrift, and in the presentations at the "BILL-60" symposium held in Oxford, UK, on January 9 and 10, 2017.