Immigrants can be forced to wait up to four and half years to secure Irish citizenship, research shows.
A study by the Immigrant Council of Ireland (ICI) found many who come to live in Ireland find the naturalisation process unjust and lengthy.
Report author Catherine Cosgrave, the ICI's senior solicitor, said the wait inflicted great stress on those looking to properly settle down and fully contribute to Irish society.
"Our research showed the processing times for applications ranged from an exceptional, one-off example of five months, through to 54 months, with many migrants reporting that they have waited far longer than the average times cited by authorities," she said.
"Migrants reported that the lengthy waiting time caused them great stress and anxiety."
The research examined the experience of 315 migrants from more than 60 countries and a wide variety of backgrounds, with 22 in-depth case studies.
Many said they were applying for citizenship to formalise their sense of having made a new home by becoming a full member of the community, while many others were looking for secure and permanent immigration status.
Ms Cosgrave said the study revealed apparent injustices in the process, including people having to wait three years for a decision, only to have their applications refused because of a change of rules during their wait.
"This research makes the need for urgent reform and the introduction of clear and fair rules abundantly clear," she said.
"While the new Government has promised to provide for more efficient processing of citizenship applications, reform must go much further to ensure our approach is fair and transparent."
ICI founder and board member Sr Stan Kennedy said Ireland's citizenship system showed a resistance to truly accepting immigration as a permanent reality for the country.
"Once we truly accept that Ireland will continue to be a diverse society in a generation's time, it becomes immediately apparent that we need to take stock of our current approach to immigration and integration laws and policies," she said.
"While other countries encourage migrants to become citizens in order to share those countries' values, Ireland could be seen to be using the process and its injustices as a way to prevent people from becoming citizens."
Sr Kennedy said the present system could lead to a permanently segregated class of people in the country.