While the Dualistic Model of Passion posits that passion can fluctuate over time, the investigation of this notion still remains understudied and is mostly assessed indirectly. This study directly examined the ongoing development of passion in a sample of young adults (N = 205) over a period of 4 months. The contribution of individual (need fulfillment) and social (perceived parental styles) determinants to the growth trajectories were also considered. Via latent growth modeling, the results showed that harmonious passion, obsessive passion, and the passion criteria had elevated levels at the initial measurement, and that passion remained high and stable over the course of 4 months. As for the predictors, parental autonomy-support predicted all three trajectories, while parental overprotection predicted obsessive passion, and psychological need fulfillment predicted harmonious passion. These findings provide a deeper insight into the temporal dynamics of passion as well as highlight key variables for fostering passion in general or harmonious passion as well as for taming obsessive passion.