"The purpose of this thesis is to investigate the methods of succession that operated in the Julio-Claudian period, from Augustus' illness in 23 BC to the accession of Vespasian in AD 69. Attention will be paid to the succession schemes, if any, of each Emperor; methods of designation employed to mark out potential successors; the growth of military influence on the succession as seen in the interventions of the Praetorian Guard and the provincial armies; and major conspiracies and their impact on the succession. Chapter I will show that Augustus, the first Emperor, whose actions in regard to the succession set the pattern for subsequent principes to follow, did not adhere to any single rigid scheme of succession as some scholars would have us believe. By means of adoption, marriage and conferral of privileges and powers, Augustus maintained a pool of imperial princes from which possible successors could be drawn. His motivation was two-fold: a concern for the continued stability of the State, and a desire to see his family, the Julian, remain in power. Tiberius (chapter II) remained loyal to his predecessor's intentions but these were thwarted by the intervention of the Praetorian Prefect, L. Aelius Sejanus. Conspiring to establish himself as Tiberius' successor, Sejanus effectively destroyed the house of Germanicus before being himself discovered and executed. Tiberius, old and virtually paranoid, did little in his last years to indicate a successor and Gaius Caligula rose to prominence with the help of Sejanus' replacement, Macro, and with minimal support from Tiberius. The assassination of Gaius and the accession of Claudius (chapter III) was the first direct intervention in the succession by the military, in this case the Praetorian Guard. The Principate was shown to be a military autocracy, Claudius coming to power only by virtue of his military support and in the face of senatorial opposition. Once established, the Emperor returned to an Augustan-style succession scheme, elevating two men as possible replacements for his natural son, Britannicus. His marriage to Agrippina resulted in the eclipse of Britannicus in favour of her natural son whom Claudius was persuaded to adopt and elevate. This was the Emperor Nero who succeeded Claudius peacefully. Chapter IV will show how Nero, feeling insecure on the throne, annihilated all his rivals from within the dynasty and so weakened its position, for those rivals were also the very people who could have provided the childless Emperor with a possible successor. Finally, a movement in the provinces led to Nero's downfall and death, and the collapse of the Julio-Claudian dynasty. With the succession thrown wide open, the army commanders struggled for power in a year of civil war which concluded when Vespasian emerged victorious to found the Flavian dynasty. We will conclude that the question of the succession was not effectively solved by the Julio-Claudians who developed ad hoc methods to indicate successors. The military, always the true basis for the Emperor's power, gradually began to realise their potential and when the dynasty collapsed army commanders fought it out to determine the next Emperor. The succession remained a source of intrigue and violence throughout our period and beyond.