For far too long, acoustical design has been popularly considered at worst a gamble, and at best a black art. If this position has ever been defensible, it certainly is not so today. In his 1932 book on the subject, Dr, Vern O. Knudsen, Professor of Physics and subsequently chancellor of UCLA, wrote: The idea, still shared by some architects, builders, and ... authorities, that the acoustical outcome of a ... building cannot be determined until the building is completed is an untenable one and can no longer be used as an excuse for poor acoustics. The acoustical outcome of a ... building is a problem in good designing and good engineering, and if the fundamental principles of architectural acoustics are incorporated in the design of the building there need be no uncertainty as to the acoustical outcome of that building - the acoustics will be good. If these principles are not incorporated, or if they are violated, there likewise need be no uncertainty - the acoustics will be bad, bad to the degree that the principles have been ignored or violated. (Knudsen, 1932) Yet eighty-one years later, we still find that buildings with good acoustics are the exception rather than the rule. In seeking a reason why this is so, one is tempted to point the finger at architects, who have little or no training in acoustics, and may overestimate the extent of acoustical knowledge they do possess. However, as in most economic markets, the clients of architects get what they demand. If a client insists on good acoustics from the inception of a project, most architects will engage the services of a competent acoustical consultant. And if the client remembers that most things worth having come with a cost, design features recommended by the acoustical consultant will be more likely to survive cost-cutting and other compromises of the building process. Finally, if communication of the consultant's recommendations to the building contractor is given a high priority, those recommendations stand a good chance of being incorporated into the building - and good acoustics will be the result. The purpose of this book is to present those responsible for providing good acoustics in performance and worship spaces an understanding of the variables and choices entailed in proper acoustic design for worship. The readership is expected to include architects, pastors, ministers of music, technical teams, and musicians. Practicing acoustical consultants may find the book a useful reference as well. The author hopes that the readers will find the level of presentation comfortable and straightforward without being simplistic