Two years ago, Allan Fernandez was like any other 6-year-old, enjoying school, friends, and playtime. But after entering second grade, his behavior changed.

“He started mouthing back and things like that,” his mother, Briana Fernandez, said. With her son no longer willing to follow directions and unable to complete simple tasks such as schoolwork, Ms. Fernandez turned to the Visiting Nurse Service of New York’s Friends Mental Health Clinic.

Tucked along the second-floor corridor of a former warehouse in the South Bronx, Friends is one of a growing number of mental health clinics geared toward children. The clinic, which opened in March, now has 35 patients and is expanding to 225 children and adolescents during the next two months.

Of the 600,000 people who use the public mental health system statewide, more than 16% are children, Jill Daniels, a spokeswoman for the New York State Office of Mental Health, which licensed the clinic, said.

The South Bronx has seven state-licensed mental health clinics, two of which are aimed exclusively at children and adolescents. Still, the demand is overwhelming: “Clients were waiting anywhere between two to four months just to get an intake at a clinic,” a program director at Friends, Jessica Fear, said.

Neighboring mental health clinics are perpetually backlogged with internal referrals or already at capacity, Ms. Fear added.

Researchers are showing that children who live in low-income areas are more susceptible to depression than children in higher-income neighborhoods, making such clinics critical. Indeed, according to a report issued by the Citizens’ Committee for Children of New York, children in Mott Haven, where the Friends clinic is situated, live in a community district at the highest risk for poverty, a problem that has worsened since 2003.

“If you fall into poverty, your mental health declines,” an author of a study on the effects of poverty on children, Lisa Strohschein, said. The study, published in the Journal of Health and Social Behavior in 2005, showed that children between the ages of 4 and 14 in low-income areas showed more pronounced cases of antisocial behavior, including bullying, cheating, and fighting.

The brightly lit Friends clinic, open Monday through Saturday and lined with board games, wooden dollhouses, and puppets, offers evening hours two nights a week to accommodate working parents. Sixty-three percent of the children come from single-parent homes, and just under 80% of patients are Hispanic, Ms. Fear said.

Most patients “are acting out behaviorally,” Ms. Fear said. “They might be struggling with ADHD, depression, neighborhood abuse, long histories of mental illness in the family, or trauma. Parents are at loss at how to manage those behaviors.”

Friends is staffed with three therapists, two of whom are bilingual. In addition to therapy with the children, the clinicians also work closely with parents, offering techniques on how best to manage their child’s behavior.

The clinic, which received funding from its umbrella organization, the Visiting Nurse Service of New York, to cover start-up costs, charges a fee for service and is Medicaid-reimbursable. Almost all clients are expected to qualify for Medicaid, the director of the clinic, Linda Embry, said.

Allan Fernandez has since become more disciplined, his mother said, adding that she expects future sessions at Friends to build on those improvements. “I expect him to continue his therapy, and his behavior to get even better,” Ms. Fernandez said.