Context :

Aims : We study dwarf galaxies in the Centaurus A group to investigate their metallicity and possible environmental effects .
The Centaurus A group ( at \sim 4 Mpc from the Milky Way ) contains about 50 known dwarf companions of different morphologies and stellar contents , thus making it a very interesting target to study how these galaxies evolve .

Methods : Here we present results for the early–type dwarf galaxy population in this group .
We use archival HST/ACS data to study the resolved stellar content of 6 galaxies , together with isochrones from the Dartmouth stellar evolutionary models .

Results : We derive photometric metallicity distribution functions of stars on the upper red giant branch via isochrone interpolation .
The 6 galaxies are moderately metal–poor ( < [ Fe/H ] > = -1.56 to -1.08 ) , and metallicity spreads are observed ( internal dispersions of \sigma [ Fe/H ] = 0.10 – 0.41 dex ) .
We also investigate the possible presence of intermediate–age stars , and discuss how these affect our results .
The dwarfs exhibit flat to weak radial metallicity gradients .
For the two most luminous , most metal–rich galaxies , we find statistically significant evidence for at least two stellar subpopulations : the more metal–rich stars are found in the center of the galaxies , while the metal–poor ones are more broadly distributed within the galaxies .

Conclusions : We find no clear trend of the derived physical properties as a function of ( present-day ) galaxy position in the group , which may be due to the small sample we investigate .
We compare our results to the early–type dwarf population of the Local Group , and find no outstanding differences , despite the fact that the Centaurus A group is a denser environment that is possibly in a more advanced dynamical stage .