This paper presents a procedure for synthesizing multilevel circuits with concurrent error detection. All errors caused by single stuck-at faults are detected using a parity-check code. The synthesis procedure (implemented in Stanford CRCs TOPS synthesis system) fully automates the design process, and reduces the cost of concurrent error detection compared with previous methods. An algorithm for selecting a good parity-check code for encoding the circuit outputs is described. Once the code has been selected, a new procedure called structure-constrained logic optimization is used to minimize the area of the circuit as much as possible while still using a circuit structure that ensures that single stuck-at faults cannot produce undetected errors. It is proven that the resulting implementation is path fault secure, and when augmented by a checker, forms a self-checking circuit. The actual layout areas required for self-checking implementations of benchmark circuits generated with the techniques described in this paper are compared with implementations using Berger codes, single-bit parity, and duplicate-and-compare. Results indicate that the self-checking multilevel circuits generated with the procedure described here are significantly more economical.