Yaroslav, known as "the Wise", struggled for power with his brothers. A son of Vladimir the Great, he was vice-regent of Novgorod at the time of his father's death in 1015. Subsequently, his eldest surviving brother, Svyatopolk the Accursed, killed three of his other brothers and seized power in Kiev. Yaroslav, with the active support of the Novgorodians and the help of Viking mercenaries, defeated Svyatopolk and became the grand prince of Kiev in 1019.

Yaroslav promulgated the first East Slavic law code, Russkaya Pravda; built Saint Sophia Cathedral in Kiev and Saint Sophia Cathedral in Novgorod; patronized local clergy and monasticism; and is said to have founded a school system. Yaroslav's sons developed the great Kiev Pechersk Lavra (monastery), which functioned in Kievan Rus' as an ecclesiastical academy.

In the centuries that followed the state's foundation, Rurik's descendants shared power over Kievan Rus'. Princely succession moved from elder to younger brother and from uncle to nephew, as well as from father to son. Junior members of the dynasty usually began their official careers as rulers of a minor district, progressed to more lucrative principalities, and then competed for the coveted throne of Kyiv. The Reign of Yaroslav I (the Wise) in Kievan Rus was height of the federation in every respect.