This document is an attempt to perform a detailed comparison of two implementations of what is widely known as a Signal/Slot library. The two libraries in question are libsigc++ (v2.x) and Boost.Signals. One of the stated goals of this comparison is to provide some initial analysis as a precursor to submission to the C++ standards body for inclusion in the standard library. libsigc++ was written/maintained by a succession of people including Tero Pulkkinen, Karl Nelson, Murray Cumming and Martin Schulze. Boost.Signals was developed by Douglas Gregor and strongly influenced by the work of Karl Nelson.