The use of lead-free components in electronic modules destined for defense applications requires a deep understanding of the reliability risks involved. In particular, pad cratering, tin whiskers, shock and vibration, thermal cycling and combined environments are among the top risks. Testing and failure analysis of representative assemblies across a number of scenarios, including with and without risk mitigations, were performed to understand reliability of lead-free assembly approaches, in comparison with leaded and mixed solder approaches. The results lead to an understanding of lead-free reliability and how to improve it, when required. This outcome is resulting in user acceptance of lead-free electronics, which is timely given the increasing scope of lead-free legislation.