What makes a group of words a meaningful structure which conveys an intended message is the arrangement of the constituents with respect to their syntactic positions in the structure in accordance with the roles they play. These roles refer to functions such as “subject”, “object”, “predicator”, “modifier” “linker”, etc. In addition to the function that it bears, each constituent has some individual characteristics which it shares with other units of the same kind. This refers to its category (which is identified on the basis of the word class membership of at least one of its constituent words) such as “noun phrase”, “adjective phrase”, “conjunction”, “quantifier”, etc. To understand how something works, we generally try to dissect it into its components to see how they behave, what their functions are, and what type of interconnections or relationships there are among them. This process is simply called “analyzing something”. Following the approach suggested by Flor Aarts and Jan Aarts in 1982, this book suggests a multi-dimensional sentence analysis which includes both sentence functions and categories in the same tree diagram. For this reason, this book is not a general language learning book, and the main aim is to provide English teachers with a set of reliable and objective criteria that can be used for the evaluation of various structural units from the viewpoint of their correctness.