He joined the University of Texas Astronomy Department in 1973 where 
he received his Ph.D. in 1978, studying
the 1975 explosion of V1500 Cygni at
McDonald Observatory.
From 1978 to 1980 he was at the Institute of Astronomy, Cambridge
where he worked with Martin Rees on
International Ultraviolet Explorer observations
of radio galaxies.
He joined the faculty of the University of Kentucky
in 1980.
The American Astronomical Society's 
Astronomy Genealogy Project lists the 17 PhDs he
has supervised.
Ferland is a Fellow of the American Astronomical Society, 
and has served on their Governing Council in addition to their Publications Board. 
He was named Fellow of the American Association for the Advancement of Science in 2023 and is a Fellow of the Royal Astronomical Society.
He is a long-time member of the International Astronomical Union where he was on the Organizing Committee of Division VI (2003-2009) 
and Commission 34 (2006-2012) Interstellar Matter.
His research involves the interactions between light
and matter, especially how the photons we receive 
can tell us about events at the edges of the Universe.
He has also studied such diverse environments
as the interstellar medium,
planetary nebulae, H II region, photodissociation regions, and Active Galactic Nuclei.
His discovery of a tidal disruption event in the Seyfert galaxy NGC 5548 was listed by Science News
as one of the top ten discoveries in astronomy in 1986.
He is best known as a developer of the Open Source 
spectral simulation code 
[https://gitlab.nublado.org/cloudy/cloudy/-/wikis/home Cloudy], a project he started at 
Cambridge in 1978.
The code uses large databases of 
atomic, molecular 
and interstellar grain cross sections and 
rate coefficients
to determine the physical state of a 
non-equilibrium plasma, the emission or absorption properties
of Interstellar clouds,
and predict the observed spectrum.
Cloudy helps to understand the emission and absorption spectra of plasmas and to interpret observational data from various astrophysical sources.
Nature Astronomy named
Cloudy their first Code of honour in their 
Access Code
series.
He has edited two books in addition to more than 700 articles on astronomy and astrophysics.
He is a co-author on the 
influential 
2006 textbook Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, written with Donald E. Osterbrock of 
Lick Observatory and the University of California at Santa Cruz.
As a science communicator, Ferland has given popular-level
talks at the Smithsonian Institution, the 
Cleveland Museum of Natural History,
and numerous clubs, organizations, and classes across the 
Bluegrass region.