This is an open access title available under the terms of a CC BY-NC-ND 3.0 International licence. It is free to read at Oxford Scholarship Online and offered as a free PDF download from OUP and selected open access locations.The Republic in Danger offers a new interpretation of Roman political history for the years 6 BC to AD 16, focusing especially on the rise of Tiberius Caesar and his succession to Augustus, the founder of the Principate. The volume proposes a new and compelling model for understanding the end of Augustus' reign and the succession of Tiberius. While Tiberius' rise to supreme power was at the expense of Augustus' grandsons, who were all dead by the time Augustus was laid to rest, their supporters remained unconvinced that life was possible under the rule of Tiberius. The result was an alliance between the enemies of Tiberius and M. Scribonius Drusus Libo. Drusus Libo, an aristocrat connected to the house of the Caesar, committed suicide in AD 16 while on trial for treason. Pettinger argues that Drusus Libo's prosecution was due to his alliance with Tiberius' enemies who were planning to destroy his government and replace tyranny with republican democracy. Pettinger offers a comprehensive analysis of the struggle between Tiberius and the supporters of Augustus' grandsons, which has repercussions for our understanding of the creation of the Principate at Rome.