Can behavioural economics help to make better labour law? This article traces the relationship between empirical work and legal thought, and focuses on new studies in behavioural economics and their potential implications for labour policy. Work by behavioural economists, and its implications, is discussed in four main fields of labour law policy: the effect of fair pay on the motivation to work; the effect of security in pay, and potentially job security, on productivity; the relevance of participation rights and job satisfaction in the workplace; and the differences between opting in and opting out of workplace schemes such as occupational pensions. Studies on these questions provide evidence that labour rights which correct inequality of bargaining power, protect security in pay and conditions and promote workplace participation redress significant market failures. If the thinking is careful and slow, behavioural economics seems indispensable to make better labour law.