Over the past two decades, remarkable progress has been made in research focused on the synthesis of 1D NWs leading to the rational design and synthetic control of key properties, where the capability of design and control of NWs has opened up the potential for revolutionary advances in diverse areas ranging from electronics and photonics to energy and healthcare. Scaling NW diameters to the deep nanometer and even molecular regime, as well as controlling their morphology, composition and structure represents fundamental challenges critical to exploiting NWs for applications in science and technology. In this chapter, we overview major bottom-up strategies for the synthesis of NWs, including vapor phase, templated, and solution-based methods. The advantages and challenges of different methods will be discussed, with representative examples illustrated.