Objective: Electrical status epilepticus of sleep (ESES) is a rare childhood epilepsy that is associated with a distinct neuropsychological regression. Typically, ESES consists of bi-hemispheric epileptiform activity, however, we present an 8-year old patient with focal right hemisphere ESES. Despite the unusual focal nature of the presentation, neuropsychological regression remained characteristic. Therefore, the current case extends limited knowledge. Method: Language milestones developed within normal limits while motor skills were delayed. The patient's first febrile seizures occurred at age four (9/2009 & 1/2010). Two non-febrile seizures were also reported (5/2011 & 2/2012). In 2010, EEG showed frequent occipital right hemisphere epileptiform discharges. Eight subsequent EEGs have documented progressively increased severity of right hemisphere spike and wave activity with current frontal maximal activity. The patient met diagnostic criteria for ESES in August of 2011. Neuroimaging is within normal limits. Historically, the patient's epileptiform activity has remained treatment resistant. Results: Intellectual functioning has declined over time (2010 WPPSI-3 FSIQ = 116; 2011 WISC-4 FSIQ = 103; 2012 WISC-4 FSIQ = 92; 2013 WASI-2 FSIQ = 85). Attention difficulty is the most prominent area of concern across assessments. Additionally, working memory, executive functioning, and processing speed indices are consistent areas of weakness. Across all evaluations, verbal and memory skills emerge as relative strengths although these also show a downward trajectory over time. Conclusions: There is evidence of clear normative neurocognitive declines over time. Generalized ESES is associated with overall disruption of cognitive functioning. Similarly, this patient has shown global cognitive decline, even within the context of focal right hemisphere ESES.