Successful capitalization and feelings of gratitude are both dependent upon perceived responsiveness of a social partner, but they are understudied in combination and have yet to be studied jointly in a daily context. Taking a new approach to studying capitalization, the current study examines the effect of daily capitalization on momentary gratitude and investigates the role of the capitalizer's typical perceived responses to capitalization attempts (PRCA) on daily gratitude and future capitalization attempts. Age and social closeness are studied as amplifiers, as older adults prioritize positive emotional experiences and it is more common to capitalize with closer others for whom the capitalizer's good news is salient and who are thus motivated to provide support to the capitalizer. Participants (N = 290) aged 25-85 years completed a trait-level survey followed by ecological momentary assessment surveys (six per day) for 10 days. Results demonstrate that people experienced higher daily gratitude when capitalizing, especially when interacting with a social partner rated as high in closeness. Those who had higher trait active-constructive PRCA also experienced higher daily gratitude, with this effect strengthened among older adults. Perceived responses were also associated with more attempts to capitalize in daily life. This work suggests engaging in capitalization and perceiving regular enthusiastic and supportive responses to one's capitalization attempts have daily emotional and behavioral benefits. Notably, regular enthusiastic responses to capitalization attempts may be a motivator for future attempts across adulthood, but it may be particularly likely to foster feelings of gratitude in old age. (PsycInfo Database Record (c) 2024 APA, all rights reserved).