The C-OAR-SE procedure is a new method for developing scales to measure marketing constructs. It is based on content validity, established through expert agreement after pre-interviews with target raters. The procedure involves six steps: Construct definition, Object classification, Attribute classification, Rater identification, Scale formation, and Enumeration and reporting. Constructs are defined in terms of Object, Attribute, and Rater Entity. Object classification determines whether the construct is concrete singular, abstract collective, or abstract formed. Attribute classification identifies whether the attribute is concrete, formed, or eliciting. Rater identification determines the type of rater entity (individual, expert, or group). Scale formation involves creating items that measure the construct, and Enumeration and reporting involves reporting the results. The C-OAR-SE procedure provides a framework for determining when to use single-item or multiple-item scales and when to use an index of essential items rather than selecting unidimensional items with a high coefficient alpha. The Rater Entity type largely determines reliability, which is a precision-of-score estimate for a particular application of the scale. The procedure is grounded in rationalism rather than empiricism and relies on logical arguments and expert agreement rather than empirical tests. Content validity is essential for scale development, and it should not be confused with face validity. The C-OAR-SE procedure provides a framework for construct definition and is applicable in marketing and other social sciences. The procedure is illustrated with examples and is designed to improve the validity and reliability of marketing scales. The procedure is discussed in detail, including the classification of objects, attributes, and raters, and the development of scales. The procedure is contrasted with traditional methods and is shown to be more effective in ensuring the validity and reliability of marketing scales. The procedure is summarized in a table and is illustrated with examples. The procedure is discussed in detail, including the classification of objects, attributes, and raters, and the development of scales. The procedure is contrasted with traditional methods and is shown to be more effective in ensuring the validity and reliability of marketing scales.The C-OAR-SE procedure is a new method for developing scales to measure marketing constructs. It is based on content validity, established through expert agreement after pre-interviews with target raters. The procedure involves six steps: Construct definition, Object classification, Attribute classification, Rater identification, Scale formation, and Enumeration and reporting. Constructs are defined in terms of Object, Attribute, and Rater Entity. Object classification determines whether the construct is concrete singular, abstract collective, or abstract formed. Attribute classification identifies whether the attribute is concrete, formed, or eliciting. Rater identification determines the type of rater entity (individual, expert, or group). Scale formation involves creating items that measure the construct, and Enumeration and reporting involves reporting the results. The C-OAR-SE procedure provides a framework for determining when to use single-item or multiple-item scales and when to use an index of essential items rather than selecting unidimensional items with a high coefficient alpha. The Rater Entity type largely determines reliability, which is a precision-of-score estimate for a particular application of the scale. The procedure is grounded in rationalism rather than empiricism and relies on logical arguments and expert agreement rather than empirical tests. Content validity is essential for scale development, and it should not be confused with face validity. The C-OAR-SE procedure provides a framework for construct definition and is applicable in marketing and other social sciences. The procedure is illustrated with examples and is designed to improve the validity and reliability of marketing scales. The procedure is discussed in detail, including the classification of objects, attributes, and raters, and the development of scales. The procedure is contrasted with traditional methods and is shown to be more effective in ensuring the validity and reliability of marketing scales. The procedure is summarized in a table and is illustrated with examples. The procedure is discussed in detail, including the classification of objects, attributes, and raters, and the development of scales. The procedure is contrasted with traditional methods and is shown to be more effective in ensuring the validity and reliability of marketing scales.