The main aim of this review is to systematize and present evidence from recent scientific studies regarding the role of early mathematical competencies in later mathematics achievement, as well as to analyze characteristics of educational and family environments that facilitate the development of these competencies in children. Presented longitudinal studies provide clear evidence that early math competencies significantly predict later mathematical outcomes. Reviewed studies also suggest that how adults and children interact in terms of mathematics activities is related to children’s mathematics development. In both formal education and family environment, adults who use everyday situations and activities for reasoning, communicating, and mathematical thinking seem to be the most important factor for fostering early math competencies. These findings are also discussed in the context of BiH where most children do not attend formal early education.