Working Welsh and Thinking Welsh are two volumes designed to build up and consolidate learners' fluency and confidence in Welsh, and focus on how common English words, phrases and constructions map onto Welsh. Working Welsh contains 200 Welsh words and phrases listed alphabetically, explained in clear and accessible language, and given ample exemplification to illustrate their meaning and use. Grammatical appendices and an English index round off the manual. Thinking Welsh contains 150 English words and grammatical and communicative concepts listed alphabetically, explained in clear and accessible language, and given ample exemplification to illustrate their meaning and use. A list of essential grammatical terms and a Welsh index round off the manual. In each book, all instances of mutation are marked with the usual typographic signs, and cross-references are given throughout to related entries. These books are innovative and ground-breaking resources for post-beginner students of Welsh, particularly within linguistic fields.