The present research examined the development of attachment bonds in adult romantic relationships using a cross-sectional internet survey (Study 1) and a longitudinal study (Study 2). Results suggested that attachment features and functions emerge in a specific sequence that begins with proximity-seeking, followed by safe haven, and finally secure base. Our cross-sectional data indicated that people who had been in relationships for longer were more likely to use their partners for attachment functions. However, in our longitudinal study, after controlling for relationship length and age, there was relatively little change in attachment features and functions over time. The data also indicated that adult attachment bonds might develop more quickly than has been previously assumed.