Earning customer loyalty is critical to business success, and B2C marketers need to be able to measure and demonstrate that loyalty to the business. Marketers predominantly rely on retention metrics to measure the effectiveness of their loyalty strategies, but that approach ignores the emotional context of customer relationships. This report will help marketers select metrics that uncover both the customer behaviors and feelings that contribute to customer loyalty. This is an update of a previously published report; Forrester reviews and updates it periodically for continued relevance and accuracy. We revised this report to reflect Forrester's updated maturity assessment model.