If Joel Fitzgerald is confirmed as Baltimore’s next police commissioner, the Philadelphia native and current Fort Worth, Texas, police chief will have a lot to learn. He’ll need a crash course in Baltimore’s neighborhoods and history, its hopes and resentments, its powerful and powerless, its juxtapositions and commonalities. Understanding all that and more will be necessary to turn around a beleaguered Police Department, re-establish trust with the community and maintain public and political support for the reforms he will need to make. Here are a few things he needs to know as he gets started.

We want an effective police force. The explosion of anger after Freddie Gray’s death did not mean that Baltimoreans don’t want or value police. A city that has suffered as much violence as we have cannot help but understand the need for effective law enforcement. We want police patrolling our streets, following up leads, solving crimes and catching criminals. The neighborhoods where alienation from the police is strongest also tend to be the ones where residents have suffered most from violence and the drug trade. We want the police to succeed.

The level of distrust cannot be understated. The refusal of witnesses to cooperate and of juries to take Baltimore police at their word is not new. That’s been around for decades. But the problem has been badly exacerbated by the Gun Trace Task Force scandal, body camera video of an officer planting evidence and other violations of the public trust. The revelations in the Justice Department’s civil rights investigation weren’t news either. But more than three years after Freddie Gray’s death, they are still raw wounds. Mr. Fitzgerald may have come into his other jobs thinking he needed to reset the relationship between the police and the community, but we’ll wager he hasn’t seen anything remotely like this.

We know the police can’t solve everything. Baltimore has been through too many police commissioners and too many policing philosophies to believe that there’s a magic solution to our crime problem. Rather, we see it as part of a tangled web of pathologies — poverty, poor education, drug addiction, disinvestment, isolation — all of which have their roots to one degree or another in Baltimore’s legacy of institutionalized racism and segregation. We expect the police to work in concert with a wide variety of public and private agencies to address the causes of crime, not just the symptoms.

We have been disappointed too many times. A police commissioner went to federal prison for misusing funds. Another was forced out after police were called to his home on a domestic violence complaint. Others stood by while profound corruption flourished in the department. One locked down a neighborhood and told the public things that proved untrue after an officer was killed. Another was ousted after a matter of weeks when he was indicted on federal tax charges. You will be greeted with cynicism. Don’t take it personally. But don’t screw up.

We still have hope. In the midst of some of the worst violence this city has ever seen, a group of Baltimoreans rallied around the idea that we could agree to stop the killings for a weekend, and then another and another. The CeaseFire movement is proof that we have not given up. The police commissioner who succeeds is the one who can harness that energy and help it spread.