Conflict monitoring and adaption processes appear associated with frontal-midline theta (fm-theta). The support for this association is found in correlational electroencephalography (EEG) studies and a few transcranial alternating current stimulation (tACS) studies and EEG neurofeedback studies. There is support for a direct association between performance on measures of conflict monitoring and fm-theta, as well as between fm-theta and conflict-related event-related potentials (ERPs) such as the event-related negativity and the N2. Anterior cingulate cortex (ACC), the generator of the frontal-midline theta oscillations, is both spatially and temporally related to these ERPs. Additionally, ACC in itself also shows activation consistent with reactivity to conflict. This network of associations to conflict monitoring uncovered using different imaging, analyses, and neuromodulation techniques may all be reflected in the fm-theta, according to the Conflict Monitoring theory. The theory proposes that theta band processes may communicate the need for control to other brain regions. This proposal that fm-theta plays a causal role via signaling the need for conflict adaption receives less support in the literature: Most studies assessing the role of fm-theta in conflict monitoring and adaption are correlational. The literature on the effects of modulating fm-theta on conflict adaption is however growing. Here the candidate uses an EEG neurofeedback paradigm to attempt to test the causal effect of fm-theta band power on conflict monitoring and adaption on the conflict component of the Attention Network Test (ANT). Five participants came to the EEG lab for a total of 6 sessions of training fm-theta power up-regulation using online feedback on band power from electrodes above the frontal-midline area as the stimulus. Participants did the ANT before and after the training. The effect of the EEG neurofeedback training was not significant; no change in power between sessions nor within blocks of sessions were found. It could thus not be tested whether fm-theta had a causal influence on the measures of conflict monitoring and adaption. This research was conducted as part of a larger project, a collaboration between Sunnås Hospital and the MICC research group, represented by René Huster. Data was collected in collaboration with Ph.D. student Mari Messel, affiliated with Sunnås Hospital.