While it is widely acknowledged that psychology is in the throes of a replication ‘crisis’, relatively little attention has been paid to the role theory plays in our evaluation of replications as ‘failed’ or ‘successful’. This paper applies well-known arguments in philosophy of science about the interplay between theory and experiment to a contemporary case study of infants’ understanding of false belief (Onishi and Baillargeon [2005]), and attempts to replicate it. It argues that the lack of consensus about over-arching theories informing both the concepts under study and the methodologies used to track them means that researchers disagree over which experiments constitute replications of the original. The second part of the paper places this specific debate within a broader discussion of the replication crisis as a crisis of ‘theory’, developing work by Muthukrishna and Henrich ([2018]) and Bird ([2018]). Bird argues that the lack of agreed over-arching theories in psychology means that a high rate of replication failure is to be expected; this paper agrees with his diagnosis but challenges his proposal that more replication will resolve the problem.