Dr. Giacalone's core research interests include understanding the origin, acceleration, and propagation of cosmic rays, and other charged-particle species in the magnetic fields of space, and general topics in space plasma physics, and astrophysics.

He develops physics-based theoretical and computational models which are used to interpret in situ spacecraft observations. He is interested in the general properties of solar, interplanetary, and galactic magnetic fields.

Currently, he is studying the origin of large solar-energetic particle events (a.k.a. solar cosmic rays) which involves a number of diverse aspects of solar physics and space physics. He has written papers describing the propagation of solar-flare particles from the Sun to the Earth where they are observed by spacecraft such as ACE, Ulysses, Wind, etc.

He is also interested in the general topic of particle acceleration in astrophysical plasmas.