Cognitive failures are minor errors in thinking reported by clinical and non-clinical individuals during everyday life. It is not yet clear how subjectively-reported cognitive failures relate to objective neuropsychological ability. We aimed to consolidate the definition of cognitive failures, outline evidence for the relationship with objective cognition, and develop a unified model of factors that increase cognitive failures. We conducted a systematic review of cognitive failures, identifying 45 articles according to the PRISMA statement. Failures were defined as reflecting proneness to errors in 'real world' planned thought and action. Vulnerability to failures was not consistently associated with objective cognitive performance. A range of stable and variable factors were linked to increased risk of cognitive failures. We conclude that cognitive failures measure real world cognitive capacity rather than pure 'unchallenged' ability. Momentary state may interact with predisposing trait factors to increase the likelihood of failures occurring. Inclusion of selfreported cognitive failures in objective cognitive research will increase the translational relevance of ability into more ecologically valid aspects of real world functioning. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.