Book excerpt: Programs to improve the performance of micro and small enterprises (MSEs) through clustering is now becoming the design of industrial and innovation policies which is implemented by policy makers in Indonesia. There has been a common perception that clusters are able to encourage entrepreneurship, learning, and productivity improvements for MSEs more effectively. This common perception, however, should be further explored whether clustered MSEs successfully obtain "collective efficiency" from clusters or they even suffer from "collective failure". This book is an attempt to reveal such issues of MSEs clustering by presenting a case study on small industrial clusters in Central Java which is well known as the "heartland" of MSEs operate in clusters. While supporting programs are persistently introduced to such clusters, in fact, to obtain "the collective efficiency of clustering" is not so easy. Unfair competition accompanied by ineffective cooperation might be factors that cause to clustered MSEs failed to gain the benefit of clustering.