Part I. Foundations of Evolution: 1. Natural selection Anna G. B. Sedlacek; 2. Sexual selection Mohammad Atari; 3. Inclusive fitness theory Carey J Fitzgerald and Brittany Lorentz; 4. Adaptive problems in the domain of human sexuality Kelly Asao; 5. Adaptations, Byproducts, and Spandrels Jaroslav Flegr; 6. Evolved psychological mechanisms: Properties and Evidence, Misconceptions and Mismatches Samuel Pearson and William von Hippel; Part II. Middle-level Theories: 7. Parental investment theory Farid Pazhoohi; 8. Parent-offspring conflict Catherine A. Salmon and Jessica A. Hehman; 9. Theory and evidence for reciprocal altruism Masanori Takano and Genki Ichinose; 10. Life history theory and mating strategies Aurelio José Figueredo and Mateo Peñaherrera-Aguirre; 11.Sperm competition theory Tara DeLecce; 12.Sexual conflict theory Ulrika Candolin; 13. Cross-species comparisons Martha Escobar, Francisco Arcediano, Zebulon K. Bell, and Jordyn Truax; 14. Cross-cultural methods in sexual psychology Marina L. Butovskaya; 15. Behavioral genetics Severi Luoto and Michael A. Woodley; 16. Sex differences and sex similarities Jessica L. Engelbrecht and John E. Edlund; 17. Individual differences in sexual psychology Aurelio José Figueredo and Catherine A. Salmon; 18. Experimental methods in sexual psychology Carey J. Fitzgerald and Jody A. Thompson; Index.