Writing for lay audiences is recognised as a  difficult task for medical writers, whose  specialised knowledge can often hinder  effective lay communication. This task is even  more challenging when preparing clinical trial  information for a paediatric population.  Involving advisory groups in the development  of clinical trial materials improves their  quality and ensures that they are fit for  purpose. This article describes how medical  writers can build successful partnerships with  advisory groups in developing assent forms  for children being approached to participate  in clinical trials.