The Pollard (also called Miao, Pollard Miao, Simple Miao or Old Miao) script was created by Samuel Pollard, a missionary working with the A-Hmao (or Large Flowery Miao) language in southern China, in the early 20th century. The script has been adapted for use by other languages in Southeast Asia. It has been revised a number of times since its inception - the form used in the 1936 Western Hmong translation of the New Testament became widespread, until the Chinese authorities in 1957 began to object to the script on the grounds of religious association and introduced a pinyin-style system. In 1988 however, Pollard's script underwent a final reform to yield the version currently in use, alongside the previous version and the pinyin system.

The Pollard Miao script is used for tonal languages and represents syllables containing an initial consonant followed by a vowel or vowel cluster. Consonants and vowels must each be explicitly expressed. There are 32 "big letters" for writing consonants and 37 "small letters" - diacritics - for writing vowels. Vowel diacritics are placed above, or at the top, middle or bottom right of the consonant. Originally the placement of the vowel indicated the tone of the syllable, however some of the reformed orthographies include separate tone marks, although these are not used consistently across languages or writing styles.

Eight of the consonants in Pollard's script can be modified by a diacritic to indicate aspiration. Some languages use these to indicate voicing contrasts, others, which require a large number of tones to be represented, use them for tone representation. Users of the script view combinations of letter + diacritic representing a process (such as aspiration) as a single chararacter, rather than two separate letters. However, diacritics which represent tone assignment or a vowel are viewed as separate letters.

Punctuation is borrowed from both the Latin and Chinese scripts.

There is also a symbol called a "wart", which is used in some orthographies to represent reduced stress on a syllable. Another, dot-like, symbol is used in other orthographies to represent reduced voicing. A third mark resembling a vertical serif is used in some areas to represent either reduced stress or reduced voicing. These three marks appear to be mutually exclusive.