This is an important question to consider as language teaching moves toward proficiency and what students are able to do with the language, rather than the more traditional focus of what students know about the language.
Many times, teachers are required to use a particular textbook, while in other situations they have choice or can be part of the decision-making process. Here is a helpful Textbook Evaluation Instrument Based on the ACTFL Standards. Essentially, this document will guide educators in determining how much the textbook guides students toward higher foreign language proficiency levels, based on the ACTFL Standards.
What is a teacher to do if he or she determines that the textbook that is required proves not to be as focused on proficiency as one might hope? This is actually excellent information to have. A concrete understanding of what is missing provides the teacher with a solid idea of the types of supplemental activities that need to be used in the class so that proficiency is the goal.