 Lagos Weber was born in the United States, the son of then-University of North Carolina at Chapel Hill professor and now former president Ricardo Lagos Escobar and ex-wife Carmen Weber Aliaga.Due to the constant traveling caused by the exile of his father during the military dictatorship of Augusto Pinochet, Lagos Weber was forced to complete his studies in eight different schools, finishing his secondary education at Colegio San Agustin.He completed his undergraduate studies at the Universidad de Chile School of Law, receiving his Bachelor of Law and Social Sciences degree in 1985.