Increasing sexual frequency in a regular relationship from once a month to once a week delivers a happiness boost equivalent to the happiness gain from a roughly $50,000 annual salary raise. More sex = monotonically higher happiness: The effect got larger with frequency. Sex 2–3 times a month, weekly, 2–3 times a week, and 4+ times a week all showed positive associations relative to no sex or very rare sex. Having sex at least 4 times a week was linked to a happiness increase roughly half the size of the marriage effect on happiness. The happiness-maximizing number of sexual partners in the previous year was calculated as one. Zero partners or multiple partners both correlated with LOWER happiness than monogamous frequency with a single partner. Money does not buy more sex or more partners. Higher family income had essentially zero correlation with sexual frequency or number of partners. Rich and poor Americans reported very similar sex lives. (This was one of the findings that surprised the researchers.) Married people had significantly more sex than single, divorced, widowed, or separated people. Roughly 90% of married respondents reported exactly one partner in the past year. Marriage itself had one of the LARGEST positive coefficients in the happiness equations. Typical American frequency was modest. The median person had sex 2–3 times a month. About 25% reported no sex in the previous year (higher among older women). Only about 7% reported 4+ times a week. Paying for sex or having extramarital sex was associated with LOWER happiness. Homosexuality had no statistically significant effect on happiness in their equations. Highly educated women tended to have fewer partners. In a time of declining marriage rates, falling sexual frequency among young adults, rising loneliness, and cultural messaging that endless novelty and “options” are the path to fulfillment, the data points the other way. The people reporting the HIGHEST happiness were disproportionately those having consistent sex with exactly one partner. * This is a correlational pattern across 16,000+ people.