A study investigated the validity of three theories in predicting the structure of language tone systems containing level tones. The theories include the following: that (1) phonetic elements are arranged so they are maximally separated in a fixed phonetic space; (2) a system with a larger number of phonetic elements will use a larger phonetic space to contrast the elements; and (3) as the number of elements becomes larger, additional parameters are added to the phonetic space to distinguish the elements. An analysis of level tones was performed on tone loans in three Hausa languages (Gwari, Nupe, and Kpan) and Xu and on the speech of five male native speakers of at least one African language with two level tones and one language with three level tones. It is concluded that tones are not separated according to a maximal spacing principle, but that a larger number of contrasting elements will occupy a larger phonetic space than will a smaller number. However, different phonetic subsystems may differ in the way that this expansion is achieved. Another striking finding is that tone borrowing is often shaped by the surface phonology of the donor language. A 55-item bibliography is included. (MSE)