Quantitative relaxometry affords a unique opportunity to map dynamic patterns of white matter development. Nonhuman primates offer a valuable model for investigating neurodevelopment, however, NHP studies utilizing relaxometry based approaches have been limited. Here, we utilize R1 relaxometry to map maturation in 35 rhesus macaques scanned across 5 timepoints during the first year of life. R1 is observed to rapidly increase during this period, with average and individual patterns exhibiting a logarithmic-like trajectory. Results highlight the onset of myelin during this period of development and demonstrate relaxometry to be a promising approach for characterizing patterns of early brain development.