People with a lower socioeconomic status and people with a migration background have lower vaccination rates than average. What socio-psychological factors are associated with vaccination uptake? The RIVM SocioVax program has conducted literature research on this topic. It appears that vaccination uptake is influenced by what people think and feel, social processes, and the perceived accessibility of vaccinations. To support an informed choice, efforts are needed in all of these areas. Relatively little is still known about the role of emotions and social processes in groups with lower vaccination rates. There may be opportunities for interventions there that could reduce inequalities in vaccination uptake.