This paper describes the development of a scale for measuring top management commitment towards continual quality performance improvement in small and medium-sized enterprises (SMEs). A set of self-assessment questions of the ISO 9004: 2000 Standard was used to assess the adoption status of quality management practices. This paper investigates the inter-item reliability and the content validity of the Quality Management Principles Scale (QMPS) in an integrated improvement process in SMEs. An empirical study was conducted to acquire senior management views on the use of the QMPS in manufacturing sectors in Trinidad and Tobago. Based on 328 responses from 110 SMEs, statistical software packages were used to analyse the empirical data and determine the reliability and validity of the QMPS. The paper contributes to develop a self-assessment scale that can be used to measure top management commitment. It is anticipated that the findings would provide practical insights for evaluating the levels of maturity on performance improvement in SMEs.