Cint is an interpretation system for the C programming language. Like most interpretation systems, it provides "load and go" type execution as well as enhanced debugging and performance analysis tools. Cint consists of two phases--a translator and an interpreter. The translator compiles the source program into code for a virtual machine. The interpreter then loads and executes this code. While providing services similar to traditional interpreters, Cint differs from them in two important ways. First, the virtual machine languages used by many interpreters are quite large; machines with 100 to 200 operations are common. In contrast, Cint's virtual machine has only 63 operations. Second, to achieve acceptable execution speeds, interpreters are often implemented in the assembly language of the host machine. Cint, however, is written entirely in C and is therefore portable. In fact, it has been transported to four machines without modification. Despite the compact size of the virtual machine language and the high-level language implementation, Cint's execution speed is comparable to that of other interpreters. This paper describes the design of the virtual machine, the implementation of the interpreter, and the performance of the system.