1. The origins of mouse genetics and the discovery of the T-locus 2. The evolutionary modern synthesis, t-haplotypes in the wild, and reproductive isolation 3. Linkage studies, cytogenetics, and the discovery that t-haplotypes consist of a series of inversions-an over-the-Century Project 4. Developmental genetics and recessive t-lethals 5. More population genetics with particular attention to the effects of t-allele mediated transmission ratio distortion 6. Mutation studies including those targeting the T/t-complex-a century long project 7. Immunogenetics and the failed search for t-antigens-from mid-century and continuing to it's end 8. Gametogenesis and the genetics of gametes, including t-haplotype segregation distortion 9. The cloning era and the cloning of Brachury and other T/t complex genes 10. X-inactivation, epigenetics, and imprinting, including of the T/t complex 11. Sex determination, sex differentiation, and the Y chromosome-a mostly last quarter of the century effort 12. Pharmacogenetics-a mostly last half of the century effort Book Bibliography