This is a guide to the CLR, the core technology underpinning .NET. Readers should take heed of the preface by seeking initial .NET exposure elsewhere and to be prepared to reread some chapters. Familiarity with C#, COM, design patterns and CIL/Metadata will assist the programmer in tackling this concise yet challenging book.

Of the '.NET Development Series' books I have looked at, this is the densest. There are a few places where I felt more elaboration or diagrams may reduce the difficulty for readers. However, for a subject previously deemed too big for single book a distilled content of 400 succinct pages is a remarkable achievement.

A language neutral description of the CLR is provided, relying mostly on C# for examples. This permits more detail and scope coverage than other language-specific CLR related books, such as 'Inside Microsoft .NET IL Assembler', which is, incidentally, a good complement to this book.

Each chapter focuses upon incremental building blocks of CLR fundamentals to deliver a rounded view of the CLR. The authors provide valuable insights regarding meaning and typical usage of key classes and good judgement regarding details thought to be misleading.

Although the publication date is relatively early, November 2002 for version 1 of the CLR, I found the book consistent with .Net 2003; care is taken to delimit descriptions of implementation details that may change in future releases.

In summary, this is a well thought out guide that conveys clarity to an illusive yet core facet of .Net programming technology. Recommended.