The development of concurrent object-based programmig languages has suffered from the lack of any generally accepted formal foun ion for de finn their semantics. Furthermore, the delicate relation p between object-oriented features supportin reuse an operation features con n g in teraction a n state chan is poorlyun rstood in a con urren t settin To address this problem, we propose the developmen t of an object calculus, borrowi n heavily from relevan t work in the area of process calculi. To this en we briefly review some of this work, we pose some i ormal requiremen ts for an object calculus, an we present the syntax, operation seman tics an use through examples of a proposed object calculus, called OC.