- The study examined the association between immigrants' adaptation-as reflected by host-country language proficiency (based on self-ratings)-and their children's psychological well-being in two countries: Germany and Israel. The findings stressed the importance of children's gender in the study of parent-child dyads. Our separate analyses of boys' and girls' subsamples revealed results that were undetected when we analyzed the subsamples of both genders together. Specifically, we found that self-reported paternal proficiency in the German language was positively associated with their daughters' psychological well-being, whereas maternal proficiency in German was positively associated with their sons' well-being. No association was found in our Israeli sample between immigrant language proficiency and their children's psychological well-being during the first 3.5 years following migration. Further analyses demonstrated that in Germany, the quality of father-daughter communication mainly accounted for the association between paternal language proficiency and their daughters' psychological well-being, while maternal psychological well-being mediated at least partially the association between maternal language proficiency and sons' psychological well-being. The results are discussed in light of the differences and similarities in the settings of the two countries.