Taichung: Maryknoll, 1984–85.
Format: Paperback and CDs
With a total of over 1,300 pages, this series is the most comprehensive set readily available for learning Taiwanese. Written in English and Pe̍h-ōe-jī throughout, with Mandarin Character glosses for new vocabulary, these books (and accompanying CDs) offer sufficient lessons to help a learner achieve a good conversational level of Taiwanese.
By virtue of being issued by a Catholic mission (and originally written for missionaries) the vocabulary and dialogs are more Christian-oriented than most language textbooks - the words for 'Catholic priest', 'Protestant minister' and '(Religious) Sister' all appear in the first few chapters of the book. For many learners of Taiwanese this is not vocabulary they will need to employ very often.
Nevertheless, this series still represents the best investment for the beginning and intermediate student of Taiwanese. Maryknoll also issue versions of the same series with source languages of Mandarin, Korean, Spanish, and Vietnamese.