There are frequent calls to enhance citizens' trust in government to pave the way towards a new paradigm of participatory governance and strong citizen support for government. In various realms, citizens may directly or indirectly engage with the government through various available mediums, even though, despite the availability of various policies and services provided by the government, citizens are generally passive and adamant in trusting the public sector. While many studies have explored a set of determinants that influence citizens' trust in government (i.e., central government, local government, parliament, and the legal system), few studies have ascertained the relationship and the role of social trust, happiness, governance, and political systems. These are critical factors that may influence trust in government. To address this gap, this study draws on the theoretical lens of social capital theory, proposing that cognitive social trust and citizen happiness—environment and performance—are the most likely predictors of citizen trust in government. This study assumes that citizens' perceptions of governance and political systems will moderate the effect of social trust and happiness on trust in government. Using data from the Asia Barometer Survey 2007, and focusing on data collected from the Philippines, this study tests a latent model employing the structural equation modelling technique. It finds that happiness negatively predicts trust in the central government and the legal system, while all other predictors do not have a significant effect. The findings also show that the political system moderates the impact of social trust and happiness on trust in government. Finally, this article points out its theoretical, empirical, and practical implications and provides directions for future research.