The fourth annual Parker Solar Probe conference, Parker Four, will be held at Johns Hopkins APL in Laurel, Maryland, from May 5 to 9, 2025. Open to the entire community, this conference will highlight discoveries from all solar encounters, including data from Parker Solar Probe’s closest approach on December 24, 2024. Contributions from other space missions and ground-based observatories are also welcome. We invite abstracts from the solar, heliospheric, and plasma physics communities, encompassing theory, simulations, data analysis, and coordinated observations. Presentation formats include oral, poster, and splinter sessions. Abstracts can be submitted before registering. Abstracts are due March 1, 2025. The registration deadline is April 1, 2025.