This textbook boosts the confidence of persons teaching Spanish as a second language, who may lack confidence in their understanding of tricky areas of expression. Their previous training did not enable them to control (much less explain to others) the many "danger zones" which challenge graduate students serving as teaching assistants, in-service teachers, and others who use Spanish professionally. It offers original and insightful analyses, abundant examples and helpful English comparisons. It disarticulates the machinery of grammar into manageable parts. It is not intended for those beginning to learn Spanish (since it skips the basics to focus on the "rough spots"), but is directed to those who know Spanish well, yet need to overcome their nagging limitations in obtuse areas, e.g. subjunctive, reflexives, pronouns (neuter, relative, personal), adjective placement, ser/estar, preterite/imperfect, commands, gender, passive and impersonal expressions. There are special sections devoted to words easily confused with each other, use of the accent mark, irregular verbs, and sentence structure. It is useful for self-study and to supplement texts in composition, culture and linguistics courses. It benefits native-speaker teachers unfamiliar with the "why" of their language, as well as buttressing anglophone instructors of scant linguistic background. The result is a better prepared teacher and a more promising learning experience for the students.