This volume contains the invited contributions that were presented at the Predeal International Summer School in Nuclear Physics 2006. It covers the recent achievements in the fields of nuclear structure, double beta decay, nuclear multifragmentation, kaon and dilepton production in heavy ion collisions, and the quark-gluon plasma. The treatment is both theoretical and experimental, with emphasis on the collective aspects and related phase transitions. The papers are authored by many leading researchers in the field.