As with everything in life, the reality can be more challenging than the theory. This chapter contains a selection of the challenges you may encounter during implementation. These range from the semantic challenges faced in a heterogeneous environment, through to adequate governance, tooling, skills, and funding. The discussion in this chapter is not intended to discourage SNOMED CT® implementation, but instead to highlight some of the things to be aware of as you embark on the journey. As they say—to be forewarned is to be forearmed.