Belarusian and Russian are the official languages according to the Constitution of Belarus (Article 17). The constitution guarantees preservation of the cultural heritage of all ethnic minorities, including their languages (Article 15).
Russian, and not Belarusian, is the dominant language in Belarus, spoken normally at home by 70% of the population (2009 census). Even among ethnic Belarusians nearly 70% normally speak Russian at home. Ukrainians and Jews also speak mostly Russian. Poles are the ethnic group who most frequently use Belarusian at home (41%), but the rest speak mainly Russian, with around 1% reporting Polish as the language exclusively used within the family.1
In everyday life many Belarusians, especially in Rural areas use Russian-Belarusian mixed language, relatively recently called "trasianka".