The PSNI is seeking more people from Catholic and working class backgrounds and the LGBT community as part of its new recruitment campaign.
Chief Constable Simon Byrne said the service needs to be "representative of the community we serve".
His comments came during a presentation hosted by Mid and East Antrim Policing and Community Safety Partnership at Carrickfergus Town Hall on Thursday night.
Mr Byrne, speaking ahead of a recruitment drive which opens next week, said: "We need to encourage more people from a Catholic background, more women, more people from working class communities, both nationalist and unionist and more people from minority ethnic communities and more people from the LGBT community."
He said that he was "particularly concerned about recruitment from the Catholic community and under-represented groups" which he believes "is stalling and risks slipping backwards".
He added: "A police service anywhere in the world will always be more effective if it is reflective of the make-up of the community it serves."
Overall, there are 6,848 police officers in Northern Ireland.
According to PSNI statistics, 66.6% are perceived as Protestant and 32% as Catholic.
The Chief Constable said "ultimately any decision on 50:50 is a political decision".
A 50/50 recruitment policy refers to the employment in equal numbers of recruits from Catholic and Protestant backgrounds.
"I believe it is a tool that has provided results in the past and should not be dismissed in the future," he added.
"It would, however, be wrong to believe that 50:50 in itself would solve the issue. It may be an effective short-term fix but we need to find a long-term solution too.
"There are some real challenges for people considering a career in policing. The security threat is very real and enduring.
"The unresolved approach to dealing with the past impacts on people's confidence and trust in policing today."
Mr Byrne said PSNI officers are "contributing every day to supporting and protecting our community".
"The police service belongs to everyone and every part of the community should feel they have an opportunity to be part of our team," he added.
Chief Inspector Michael Simpson reiterated the importance of the PSNI being "representative of the community we serve" and a "diverse workforce".
"People ask what are the barriers to joining the police. We want more people to view it as normal," he said. "The security threat in Northern Ireland is severe. That is very real."
He said new recruits must be prepared to serve in any part of Northern Ireland although the PSNI tries to "facilitate people close to home".
Applications will be accepted online from February 4 until 25.