Solders are an integral part of electronic packaging. Recently, there has been a significant drive to replace Pb-Sn solders with Pb-free, environmentally-benign solders. Given the widespread use of Pb-Sn solder in the manufacture and assembly of circuit boards, the development and reliability of new Pb-free solders is crucial for the successful substitution of these materials in the electronics industry. In this talk an overview of the thermomechanical behavior and microstructure in Pb-free solders, in bulk form and at small length scales, will be presented. Experiments coupled with microstructure-based simulations have been conducted to further the understanding of deformation in these materials. The challenges and opportunities for metals research in this arena will be explored and discussed.