This study investigated the effects of the proximity to city parks and the influence of residential greenness on children's emotional and behavioral problems. This cross-sectional study included 1,468 mothers of children (ages 4 to 6) who were residents of the city of Kaunas, Lithuania. The mothers and their children were enrolled in the FP7 PHENOTYPE project study. The mothers reported on their parenting stress and their children's mental health. Residential greenness was characterized as an average of the satellite-derived normalized difference vegetation index (NDVI) in a 300 m buffer around each home address, and the proximity to city parks was defined as the distance from the subject's residence to the nearest park. Linear regression models were used to investigate the association among the residence distances from city parks, greenness and children's mental health problems. Farther residential distance from city parks was associated with worse mental health (except for the emotional problems subscale) in children whose mothers had a lower education level. More residential greenness was associated with worse mental health (more conditional problems and less prosocial behavior) in children whose mothers had a higher education level. These relationships have important implications for the prevention of emotional and behavioral problems in children.