We are pleased to publish this issue of the Children’s Research Digest on the theme of “Archiving Evaluation Data”. With increasing emphasis on programme, service and process evaluations, immense amounts of rich evaluation data are now being produced. To optimise the value of this data and to extend the learning from evaluation studies, more and more people, organisations and institutions are starting to archive their data in order to optimise its use and encourage other researchers to conduct secondary analysis. This is a hugely worthwhile endeavour but is not without risks and considerations. In this volume of the Children’s Research Digest, authors deal elaborately with the many dilemmas, difficulties and aspects of archiving evaluation data.

We would like to thank all authors and the reviewers for their contributions to this issue. Special thanks are also due to all who helped with proof reading and to AAD for providing the design and layout. We would also like to thank Jane Gray for acting as Guest Editor and Atlantic Philanthropies for their ongoing involvement in the Prevention and Early Intervention Research Initiative.

This special edition of the Digest originates in the Prevention and Early Intervention (PEI) Research Initiative which is an ongoing archiving project at the Children's Research Network. The PEI Research Initiative is funded by The Atlantic Philanthropies with the aim of adding further value to Atlantic’s investment into 52 Prevention and Early Intervention programmes in Ireland and Northern Ireland between 2004 and 2015. The central objective of the PEI Research Initiative is to make preservation versions of evaluation research data accessible for further use, via the national data archives (ISSDA, IQDA and UKDA). Additional dissemination activities from the PEI Research Initiative include capacity building in prevention and early intervention, evaluation and data re-use. This special issue of the Digest will contribute a valuable and timely publication on the processes, motivations and risks of archiving of evaluation data.