Paediatric parenteral formulation development is a complex and multifactorial process. It requires careful consideration of the route of administration, choice of excipient and age-appropriate formulation alongside an understanding of the challenges associated with paediatric drug administration. These considerations and challenges vary depending on the physiological development of the child, access to the route, pharmacokinetics (absorption, distribution, metabolism, excretion) and toxicity characteristics of the drug and formulation. Formulation considerations in relation to parenteral administration to neonates are similar to those for paediatric patients but with additional concerns and considerations. Acceptability and pain felt by the patient, especially for chronic diseases where co-operation and adherence may become problematic, should also be taken into account. It should be remembered that the youngest children and neonates often cannot verbally communicate the pain experienced. The formulation development strategy also needs to take into consideration the global locations of the target population, often rural, resource-limited settings in developing countries. These present issues such as lack of cold storage, shortage of sterile diluents and administration equipment and increased risk of infections. This chapter addresses the major considerations which should be taken into account with respect to paediatric parenteral formulation development.