Countries with high levels of social trust, where citizens generally believe others are trustworthy and cooperative, consistently rank highest in international happiness surveys. Norway, Denmark, and Finland, which lead global trust indices, also dominate happiness rankings. Conversely, countries with low social trust, such as those that have experienced recent civil conflicts, rank poorly on happiness measures. Building social trust must therefore be the key to improving national wellbeing. Governments should prioritise policies that foster trust between citizens, such as community programmes and civic education. If we can increase social trust, we will create happier societies.