There are calls for more support for foreign prisoners at Morton Hall jail near Lincoln.
Two thirds of the women inmates are foreign nationals, many of whom are serving time for smuggling drugs.
In a report, the Prison Reform Trust says although the jail has taken positive steps to address the needs of the inmates, it needs to do more.
The prison still does not have a proper foreign national policy and says staff should be given more training.
Enver Solomon, who wrote the report, felt Morton Hall needs to build on the work it has already done.
He said: "There needs to be extensive staff training so they are aware of specific cultural issues related to having such a large foreign national population.
"And the prison needs to be supported with extra resources from prison service headquarters."
A Home Office spokesperson said: "The Prison Service holds foreign nationals from a range of countries whose needs vary widely.
"We aim to treat them as individuals addressing their particular needs both as prisoners who have committed offences and as foreign nationals."