Essential to the study of the Mesta in New Spain is the publication of the text of its constitution, not too available in Spanish, in English dress. This document throws new light on the relation of government to the pastoral industry, up to the present a sadly neglected aspect of Spanish colonial history. The importance of the problem is evident in view of the wealth and extent of the sheep and cattle business, and its relationship to the whole economy of New World colonization. Any adequate study of the grazing industry in New Spain would be impossible without some knowledge of the Mesta constitution of 1537, the basic instrument which regulated this industry until 1574; in the latter year the constitution was changed by the addition of numerous amendments which indicate considerable growth in the pastoral industry. Unfortunately, the minutes of the semiannual meetings of the Mesta have not been uncovered, if indeed they exist at all. Such documents would provide a picture of the grazing industry in operation and would be useful in a more complete investigation of the subject.