This book contains the refereed proceedings of the 1st International Conference on Lean Enterprise Software and Systems, LESS 2010, held in Helsinki, Finland, in October 2010. LESS 2010 is the first scientific conference dedicated to advance the body of knowledge for lean enterprise software and systems development. To achieve this goal, it offers a unique platform by bringing together leading researchers and industry practitioners – in fact, more than 60% of the conference speakers come from industry. The 24 papers selected for this book represent a diverse range of experiences, studies, and theoretical achievements. They are organized in three tracks on Scaling Agile to Lean, Lean Product Development and Innovation, and Beyond Budgeting. The volume is completed by two invited talks and the summary of the panel on Why Agile, Why Lean.