This paper makes available to the broader educational community the instruments which have been originally designed and validated within the European project "CLIL for all: Attention to diversity in bilingual education" ("ADiBE") to determine how diversity is being catered to across a broad array of CLIL contexts in European Secondary Education (Austria, Finland, Germany, Italy, Spain, and the United Kingdom). They include three sets of questionnaires, interviews, and observation protocols and are qualitative and quantitative instruments whose design has been based on the latest research and which have undergone a carefully controlled double-fold pilot process for their validation (external ratings approach and pilot phase with a representative sample of 264 subjects). The questions included in the three sets of instruments are initially characterized, together with their format and main categories. The paper then details the steps undertaken for their research-based design and the double-fold pilot process followed for their validation. The questionnaires and interview and observation protocols are then presented in a format which is directly applicable in any CLIL classroom in order to determine the accessibility of bilingual programs for all types of achievers and to identify the chief difficulties and best practices in promoting inclusion in bilingual education.