For its spelling authority the New Handbook of Texas has generally used Webster's Ninth New Collegiate Dictionary (1983) and its successor, Merriam Webster's Collegiate Dictionary (Tenth Edition, 1993). American spellings are used where possible, though the occurrence of British spellings in proper nouns often requires an exception; theatre is probably the most common British spelling in the New Handbook.

Misspellings that occur in quotations are not marked by sic. The editors have attempted to quote accurately and to avoid sprinkling editorial exculpations around.

The numerous variant spellings of names of Indian groups result in general from the wide variation in how Europeans heard the names. Frenchmen heard and spelled group designations differently from Spaniards, and Anglo-Americans heard and spelled something else again. Moreover, individual Spaniards, for instance, multiplied spellings from person to person. One Franciscan heard and wrote one thing, and the next heard and wrote differently. To compound the difficulty, authors of secondary works sometimes introduced new terms or took as group designations words that denoted something else. The occasional consequence is a dazzling array of different spellings of the same word, or, occasionally, a group name that denotes no group. The editors have followed the lead of the first edition of the Handbook and its Supplement in the entry forms of Indian group names. This does not, however, imply that these are the "right" spellings; they are merely convenient. Variant spellings are listed in parentheses.