Apolipoprotein C-III (apoC-III) is an important determinant of dyslipidemia and cardiovascular risk. The Multi-Ethnic Study of Atherosclerosis (MESA) was a large community based cohort study of CVD risk factors, subclinical measures of atherosclerosis and determinants of major CVD events. However, the relationships between apoC-III proteoforms and patterns of dyslipidemia, atherosclerosis and cardiovascular disease (CVD) risk are largely unknown. The present proposal will utilize a novel mass spectrometry immunoassay (MSIA) to investigate the relationships of apoC-III (and secondarily apo-CI and C-II) proteoforms with plasma lipid concentrations, progression of vascular calcification and carotid atherosclerosis, and development of major adverse cardiovascular events (MACE) within the MESA cohort.