A recent survey of existing syntactic models shows that none accurately describes the syntax of the English languagethat people actually use and that they inhibit rather than promote knowledge of natural language by creating a gapbetween what should be taught and learned and what obtains. To demonstrate this gap, this paper critically examinesfour recommended senior secondary school English course books to determine the extent to which they reflectexisting syntactic models’ descriptive inadequacies, and highlights the implications for language education inNigeria. Using the emerging Natural Language Linguistics (NLL) model as analytical tool, each book was carefullyexamined to identify topics on the syntactic units: sentence, clause and group. These were then critically studied,paying great attention to definitions, descriptive statements, models, and examples, and noting common features anddifferences. The bits of information pieced together constitute the data. Findings show inconsistency in modelapplication, no uniformity in, and consensus on, the number and nomenclature of syntactic units, terminologicalconfusion, descriptive inaccuracies, typological inexactness, incorrect definitions, wrong and inappropriate examples,and confusion between constituents and elements of structure. The absence of a clear-cut distinction between phraseand clause and between clause and sentence in existing syntactic models, which reflected in the books, explains theshortcomings that potentially limit learners’ knowledge and use ability. Only a syntactic model that accuratelymirrors natural language structure can positively promote language education in the Nigerian context where coursebooks are the most important English teaching-learning resource.