Drug discovery programmes are usually established after identifying suitable targets in disease with the wide range of required technologies described in this chapter. After a short background to current target discovery strategies, the main emphasis is on molecular biology, used here as an umbrella term for genomics, epigenomics, proteomics and metabolomics. Cell biology also makes an important contribution to target discovery both from a structural perspective, but also through myriad functions such as proteostasis and death pathways. A common theme running through the chapter is the move from whole tissue or cell culture analysis towards highly informative single cell analyses. Machine learning in various forms underpins all these activities and promises to revolutionise the way in which actionable targets could be obtained from seemingly intractable disease pathways.