The concepts of "explicit" and "implicit" (knowledge) are at the core of SLA studies. We take "explicit" as conscious and declarative (knowledge); "implicit" as unconscious, automatic and procedural (knowledge) (DeKeyser, 2003; R. Ellis, 2005a, 2005b, 2009; Hulstjin, 2005; Robinson, 1996; Schmidt, 1990, 1994). The importance of those concepts and components, we believe, must also be acknowledged in language teaching, and consequently in language teaching materials. However, explicitness and implicitness are rather complex constructs; such complexity allows for multiple nuances and perspectives in their analysis, and this fact poses a real challenge for their identification in the learning and teaching process and materials. We focus here on ELT materials and aim at the building of a reliable construct which may help in the identification of their potential for promoting implicit and explicit components. We first determined the features to identify the construct for implicitness and explicitness; next, we validated it and then we applied it to the analysis of the activities included in three sample units of three textbooks. The results were computed along a continuum ranging from 0 to 10 in each activity. The systematization and computation of results will hopefully offer a reliable figure regarding the identification of the degree of explicitness and/or implicitness in the materials analysed. (Contains 1 figure, 3 tables, 5 graphs and 2 notes.)