Mindfulness is theorised to improve attention regulation and other cognitive processes. This systematic review examines whether 8-week standardised and manualised mindfulness training programs such as Mindfulness Based Cognitive Therapy (MBCT) and Mindfulness Based Stress Reduction (MBSR) enhances attention, memory and executive function abilities measured by objective neuropsychological tests. Seven databases were searched resulting in 18 studies meeting inclusion criteria for review. Overall studies did not support attention or executive function improvements. We found preliminary evidence for improvements in working memory and autobiographical memory as well as cognitive flexibility and meta-awareness. Short-term mindfulness meditation training did not enhance theorised attentional pathways. Results call into question the theoretical underpinnings of mindfulness, further highlighting the need for a comprehensive theoretical framework.