My investigations into a wide variety of areas of expertise have led to me to think that Ericsson’s premise in studying expertise and expert performance is a reasonable one, and I see this book as providing support for it. However, as is befitting theories in the so-called “special sciences,” it may be that the most we can aspire to in this area is to identify principles that tend to be correct. And, indeed, this is as far as my aspirations go. For although I aim to propose a theory of all types of expertise, it is likely that there are some significant differences among individual experts within and between domains as to what goes on in their minds during performance. For example, although I shall argue that unless a situation is such that it requires actions to proceed faster than thought (and, as I shall suggest, thought can move rather fast), I claim that experts in basically any domain can typically think without this interfering with their actions. But how far does the “basically” extend, and just what type of thoughts do I permit? It is my view that the “basically” extends quite far, though I do not specify exactly how far, and although I claim that many types of thoughts are compatible with expert performance, I do not specify which are not, though I do hint that perhaps thoughts, such as entirely irrelevant thoughts or thoughts about impending doom, or even about great success, might sometimes throw experts off. In sum, I think that the types of thoughts that are compatible with performing well will be the type that have been practiced. With both the beneficial and the detrimental, then, I think that there will be individual and context-relevant differences, and for athletes it is the athletic coaches and sports psychologists who are best suited to identify what works for which individuals. Moreover, there may be differences within an individual from time to time. However, I do claim that, in general, thinking at the expert level does not hinder and at least apparently facilitates doing. And in the next chapter, the argument for this begins.