During Wave IV, Add Health collected biological specimens from a large, nationally representative sample of young adults. Given the size of the Wave IV sample, its geographic distribution, and in-home setting of the respondent interviews, biological specimen collection involved practical, relatively non-invasive, cost-efficient and innovative methods. These methods included collection of capillary whole blood via finger prick by trained and certified field interviewers, its in situ desiccation, then shipment, assay and archival of dried blood spots. The collection of capillary whole blood followed the collection of cardiovascular and anthropometric measures (Entzel et al, 2009) and saliva (Smolen et al, 2012). It preceded the collection of data on respondent use of prescription and select over-the-counter medications (Tabor et al, 2010). Further details on the design of Add Health Waves I-IV, are available elsewhere (Harris, 2011). Included in the Add Health Wave IV data are two measures of inflammation and immune function based on assay of the dried blood spots: • High Sensitivity C-Reactive Protein (hsCRP, mg/L) and • Epstein Barr Viral Capsid Antigen IgG (EBV, AU/ml) To facilitate analysis and interpretation of hsCRP and EBV, the restricted-use Add Health Wave IV data also include two data quality flags and 11constructed measures: • CRP_FLAG • EBV_FLAG • Classification of hsCRP (Pearson et al, 2003) • Count of Common Subclinical Symptoms (Vaidya et al, 2006) • Count of Common Infectious or Inflammatory Diseases • NSAID/Salicylate Medication Use in the Past 24 Hours • NSAID/Salicylate Medication Use in the Past 4 Weeks • Cox-2 Inhibitor Medication Use in the Past 4 Weeks • Inhaled Corticosteroid Medication Use in the Past 4 Weeks • Corticotropin/Glucocorticoid Medication Use in the Past 4 Weeks • Anti-rheumatic/Anti-psoriatic Medication Use in the Past 4 Weeks • Immunosuppressive Medication Use in the Past 4 Weeks • Anti-inflammatory Medication Use. This document summarizes the rationale, equipment, protocol, assay, internal quality control, data cleaning, external quality control, and classification procedures for each measure listed above. Measures of glucose homeostasis and candidate genes are documented elsewhere 3 (Whitsel et al, 2012; Smolen et al, 2012). Documentation of lipids will be provided in a separate report.