Purpose: To examine in people with neurological disorders, which method/s of providing external cues to improve task performance are most effective. Methods: Medline, EMBASE, and PsycINFO were systematically searched. Two reviewers independently screened, extracted data, and assessed the quality of the evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Results: Twenty six studies were included. Studies examined a wide-range of cues including visual, tactile, auditory, verbal, and multi-component cues. Cueing (any type) improved walking speed when comparing cues to no cues (mean difference (95% confidence interval): 0.08 m/s (0.06-0.10), I2 = 68%, low quality of evidence). Remaining evidence was analysed narratively; evidence that cueing improves activity-related outcomes was inconsistent and rated as very low quality. It was not possible to determine which form of cueing may be more effective than others. Conclusion: Providing cues to encourage successful task performance is a core component of rehabilitation, however there is limited evidence on the type of cueing or which tasks benefit most from external cueing. Low-quality evidence suggests there may be a beneficial effect of cueing (any type) on walking speed. Sufficiently powered randomised controlled trials are needed to inform therapists of the most effective cueing strategies to improve activity performance in populations with a neurological disorder. Implications for rehabilitation Providing cues is a core component of rehabilitation and may improve successful task performance and activities in people with neurological conditions including stroke, Parkinson's disease, Alzheimer's disease, traumatic brain injury, and multiple sclerosis, but evidence is limited for most neurological conditions with much research focusing on stroke and Parkinson's disease. Therapists should consider using a range of different types of cues depending on the aims of treatment and the neurological condition. There is currently insufficient evidence to suggest one form of cueing is superior to other forms. Therapists should appreciate that responding optimally to cues may take many sessions to have an effect on activities such as walking. Further studies should be conducted over a longer timeframe to examine the effects of different types of cues towards task performance and activities in people with neurological conditions.