Using longitudinal data from UCNets, we examined newly-listed alters and distinguished between truly new ties who were recently met (typically coworkers and acquaintances) and awakened ties who were previously known to ego (typically extended kin and friends). Half of the newly-listed ties among the younger respondents were truly new, whereas two-thirds among the older respondents were awakened. In both groups, however, most alters were previously listed. These ties mainly included kin, confidants, and advisors, suggesting stability in the network core. Methodological implications for the name-generating process and substantive implications for the understanding of network dynamics and structure are discussed. •This study examines which alters were mentioned for the first time in the later wave of UCNets.•Only one-third of all alters were newly-listed, suggesting stability in the network core.•Most newly-listed ties in the young cohort were truly new ties and in the old cohort were awakened ties.•Alters who were not new mainly included kin, confidants, and advisors.•Multilevel models estimate the alter and ego attributes associated with a tie being truly new or awakened.