Traditional methods of genetic improvement, both through selection programmes and proper use of breed differences and heterosis, have been effective in improving production efficiency. This improvement has been realized primarily in reproductive performance, growth rate and carcass composition. This chapter begins with a historical overview of advances in pig breeding from the end of Second World War. There remain needs for improvement in traits associated with efficiency, disease resistance, behaviour and longevity, and the next two sections review new approaches to genetic improvement with a focus on these traits.