Nanowires have been explored for many potential applications, including nanoelectronics, nanophotonics, sensors/biosensors, energy conversion and storage, and nanomedicine. While processing them, assembly and integration of individual nanowire components into functional electronics or devices remain critical steps. A variety of methods have been studied for the assembly of nanowires, such as molecular interactions (e.g., surface tension, hydrophobic force, electrostatic force), molecular linkers (e.g., antibody-antigen), or external forces (e.g., electrical, magnetic, or dielectrophoretic force). In this presentation, I will discuss several fundamental issues in the assembly and integration of multisegmented nanowires into functional electronics or systems. First, I will review several techniques on how to effectively assemble and integrate nanowires. Then, I will discuss the oxidation effect and how to mitigate or solve this problem. Finally, I will show nano-joint formation and large-scale nanowire assembly and soldering, including atomic diffusion, intermetallic formation, and void formation.