This book constitutes the refereed conference proceedings of the 21st International Conference
on Principles and Practice of Constraint Programming CP 2015 held in Cork Ireland in August
September 2015. This edition of the conference was part of George Boole 200 a celebration of
the life and work of George Boole who was born in 1815 and worked at the University College of
Cork. It was also co-located with the 31st International Conference on Logic Programming (ICLP
2015). The 48 revised papers presented together with 3 invited talks and 16 abstract papers
were carefully selected from numerous submissions. The scope of CP 2014 includes all aspects of
computing with constraints including theory algorithms environments languages models
systems and applications such as decision making resource allocation schedulling
configuration and planning.