This book proposes an updated view of the current knowledge of the molecular and cellular mechanisms ensuring axon growth and guidance. The introductory chapter will remind the readers of all the features of a growth cone and the mechanisms controlling its growth. From there, one enters a fabulous journey with a growth cone, a Tom Thumb story filled with molecular encounters and complex interactions leading to one of the most fantastic developmental achievements: the nervous system wiring. The journey starts with a description of the classical guidance signals such as the netrins, the semaphorins, the ephrins or the Slit family. The question of the exact definition of a guidance signal is addressed in a chapter which discusses whether neurotrophic factors can be considered as guidance cues. This complex question is also considered in a chapter presenting the role of adhesion molecules during axon guidance and the report of compelling evidence for a guidance effect of neurotransmitters. The diversity of the molecular cues used by growth cones to reach their targets is finally illustrated in a chapter describing the unexpected role of morphogenes as direct guidance signals.