The chapter introduces the construction of summated rating scales, a common tool in social sciences for measuring attitudes, opinions, and other constructs. The author, Paul E. Spector, emphasizes the importance of developing reliable and valid scales, which require multiple items to ensure precision, reliability, and scope. The process involves defining the construct clearly, designing the scale with appropriate response choices and item stems, pilot-testing, conducting item analysis, validating the scale, and establishing norms and reliability. The chapter also discusses the theoretical underpinnings of summated rating scales, including classical test theory, and addresses common issues such as social desirability and response bias. The development of the Work Locus of Control Scale (WLCS) is used as an example to illustrate the steps involved in scale construction.The chapter introduces the construction of summated rating scales, a common tool in social sciences for measuring attitudes, opinions, and other constructs. The author, Paul E. Spector, emphasizes the importance of developing reliable and valid scales, which require multiple items to ensure precision, reliability, and scope. The process involves defining the construct clearly, designing the scale with appropriate response choices and item stems, pilot-testing, conducting item analysis, validating the scale, and establishing norms and reliability. The chapter also discusses the theoretical underpinnings of summated rating scales, including classical test theory, and addresses common issues such as social desirability and response bias. The development of the Work Locus of Control Scale (WLCS) is used as an example to illustrate the steps involved in scale construction.