Some residents of a HSE-run centre in west Dublin for young adults with chronic conditions told inspectors from the Health Information and Quality Authority that they felt unsafe in the facility.
Inspectors were also told that it was pointless to raise issues with their care providers as nothing would be done to address them.
The watchdog failed the centre on ten of the 15 criteria it assessed and did not pass it on any of the remaining five.
The centre, which is on the grounds of Cherry Orchard Hospital, was home to 28 residents at the time of last November's unannounced inspection.
The visit followed two reviews in the previous couple of years which resulted in the facility's application for State registration being rejected.
The young male and female residents received ongoing care in two adjacent units on the Cherry Orchard campus.
Inspectors met with and observed the daily routines of all but four of the residents and spoke with six of them, with seven staff as well as with the person in charge and a representative of the HSE.
The watchdog found that residents had a poor quality of life, suffering negative impacts because of institutional staff practices, a lack of social care opportunities and poor safeguarding practices.
Inspectors were not assured that appropriate actions were taken in response to allegations of abuse or suspected abuse.
None of the staff consulted could outline the different forms of potential abuse or the reporting structure within the centre.
Some staff told inspectors they would inform alleged abusers of the allegations against them to ensure the information was accurate before escalating complaints to a manager.
Evidence of garda vetting could not be produced for three of the five agencies supplying personnel to the centre.
The HSE told inspectors it was assured that residents' money was safeguarded, inspectors found inappropriate arrangements in place.
On viewing a sample of three residents' accounts discovered that sums of €30, €41 and €128 were unaccounted for.
The person in charge said oversight of residents' money was not the responsibility of the units' staff. However, the HSE campus manager said that those staff were responsible for maintaining accurate records and for submitting them to the campus' financial office.
Following the inspection, representatives of the HSE were required to attend a regulatory meeting with HIQA and to present an improvement plan.
In a statement, HIQA says it will monitor the Cherry Orchard centre "closely to verify whether the provider's improvement plan is effective in improving the safety and quality of life" of its residents.