During 1993 and early 1994, a broadly-based group of parallel computer vendors, library writers, and application specialists met regularly to define a standard for message-passing libraries. The Standard has just been finalized (April, 1994) and is widely available [4]. A number of implementation efforts are under way, both public and proprietary, and porting of applications has begun. The MPI Forum, as it called itself, was eager to provide profiling functionality within the Standard, but believed it premature to standardize the profiling tools itself. In this paper we explain a solution to this problem, which was adopted as part of the MPI Standard. We then explain two ways to implement the specification, and illustrate the use of the MPI profiling interface with three profiling libraries that can be used with any conforming MPI implementation.