The layered ransition metal dichalcogenides (TMDs) exhibit unique phase- and thicknessdependent electronic, photonic, and magnetic properties intriguing for future device technologies. Historically, contact engineering in silicon devices has relied on a detailed understanding of the relationships between contact chemistry, phase, and resistance. However, similar relationships in metal–TMD systems are not yet understood and high contact resistance critically limits TMD device performance. This dissertation employs a variety of materials characterization techniques, such as in–situ photoelectron spectroscopies, Raman spectroscopy, and scanning probe microscopy, to study the metal–TMD and metal–Te interface chemistries, structures, and band alignments as a function of pre-metallization, in-situ metallization, and post-metallization processing conditions. The band alignments of similarly processed Schottky diodes and fieldeffect transistors are extracted analytically and corroborated with chemical and structural changes during processing. Process recommendations for consistent, high-performance contacts to MoS2 and WSe2 are provided.