In a recent career advice column for Nature, a neuroscientist asks what to do when asked to write a letter of recommendation for someone that “you cannot, in all honesty, recommend to move on to the next stage of their research career.” Nature writer Bianca Nogrady collates advice from three scientists on how to handle this situation. Maria Augusta Aurruda (Brazilian Biosciences National Laboratory) and James Murphy (Walter and Eliza Hall Institute) recommended being honest with the candidates about not being able to write them a strong reference. In cases where writing a letter of recommendation is unavoidable, Murphy and Khatijah Yusoff (University of Putra Malaysia) discuss how they would balance a positive tone with honesty about the individual’s limitations and weaknesses.