In children under the age of 5 who have abnormalities in history, physical examination, and laboratory studies indicating multi-system disease, uncovering the correct diagnosis is challenging. Here, we report the course of a 4-year-old girl who presented with a change in behavior, fever, arthralgia, arthritis, and hematuria following three recent hospitalizations for pneumonia and impetigo. Serologic findings were suggestive of a rheumatologic etiology and a renal biopsy was consistent with Membranous Lupus Nephritis Class V which helped secure the diagnosis of pediatric systemic lupus erythematosus. We review the clinical features and diagnostic criteria of early-onset systemic lupus erythematosus and discuss diagnostic considerations and prognosis.