Drawing on comparative research with children's participation practitioners in Nicaragua and the United Kingdom, this study explores the thinking that guides their practice. Earlier models are considered inadequate to describe complex, multidimensional participation processes. Whilst several differences are observed, the key issues or tensions are similar in both countries. Fifteen tensions are discussed in three categories. Most are tensions between participation as social control and participation as empowerment, which apply to all marginalised groups, not just children. The second group is specific to children. Finally, there are tensions between process and product. It is suggested that practitioners could use this analysis to reappraise and improve practice.