This paper discusses the misuse and limited usefulness of Cronbach’s alpha as a measure of reliability and internal consistency in psychological testing. The author argues that alpha has several major flaws: it always has a value, which cannot be equal to the true reliability of a test based on the interitem covariance matrix and assumptions about measurement error; it is often used as a measure of internal consistency rather than reliability; and it does not reflect the internal structure of the test. The paper also highlights that statistics based on a single test administration do not provide much information about individual test performance accuracy. The author concludes with five key points about the usefulness of alpha and suggests alternative reliability estimation procedures, emphasizing the importance of using the greatest lower bound (GLB) instead of alpha.This paper discusses the misuse and limited usefulness of Cronbach’s alpha as a measure of reliability and internal consistency in psychological testing. The author argues that alpha has several major flaws: it always has a value, which cannot be equal to the true reliability of a test based on the interitem covariance matrix and assumptions about measurement error; it is often used as a measure of internal consistency rather than reliability; and it does not reflect the internal structure of the test. The paper also highlights that statistics based on a single test administration do not provide much information about individual test performance accuracy. The author concludes with five key points about the usefulness of alpha and suggests alternative reliability estimation procedures, emphasizing the importance of using the greatest lower bound (GLB) instead of alpha.