Formulations designed to be applied to the skin are commonly used for children, particularly for the treatment of skin diseases. There are a number of important issues with regard to the use of these types of medicines in the paediatric population in comparison to adults; for example children have a greater risk of experiencing systemic side effects as a result of treatment. This chapter discusses the roles of the different formulations used for topical and transdermal treatment, their design and considerations specifically relevant for the development of these medicines for children.