Patients often line up outside the two-story brick building before the doors open. They crowd into the waiting rooms and often chaotic lobby. Security guards direct traffic and administrators calm frustrated patients. Sometimes, paramedics must be summoned for those who need to go to the emergency room.

One recent morning, Theresa Day, 50, had been waiting two hours for her appointment. A bus driver who lost her job and insurance, she tapped her finger on the chair and flipped through a novel. More than once, she walked down the hall to ask how much longer she would have to wait.

"This is awful," said Day, who suffers from rheumatoid arthritis and used to go to Kaiser. She says she never thought "in a million years" that she would need to come to a clinic for medical care.

As it struggles to care for existing patients, nearly 55% of whom are uninsured and 30% covered by Medi-Cal, the clinic is trying to prepare for more.

The main clinic is being remodeled and a new satellite office is being planned. To become more competitive, administrators are trying to shrink wait times and nurture stronger personal relationships. In the past, patients were randomly assigned to any available medical care provider. Now, the clinic is trying to ensure that patients see the same professional each visit.

To improve efficiency, the clinic invested in electronic record keeping so healthcare workers can better track patients' health, assess their needs and document improvement. They also set up an online system for patients to check lab results, make appointments and contact their doctors.

Community clinics aren't a first choice for many patients, just the best option available in their neighborhoods. But the clinics have considerable experience and training in how to manage and treat patients with chronic illnesses. Unlike private physicians, they offer additional services, such as help with transportation to appointments and finding housing.

Although community clinic patients tend to be sicker and poorer, the quality of care at community clinics rivals that of private practice physicians, according to a recent Stanford University study. Other research has found that patients who receive most of their care at community health centers have lower annual medical costs than other patients.

But the challenges are daunting. T.H.E. Clinic, like others across the nation, struggles to recruit and retain doctors because the pay is comparatively low, the pressure is high and the cases are difficult. Motivating patients to change unhealthy behaviors, show up for appointments and take medications is difficult.

Nurses and medical assistants can tell obese or diabetic patients about the necessity of healthy eating, only to see some later show up drinking soda and eating chips. "You can't help them if they don't want to help themselves," says Sandy Canas, a medical assistant.

Socioeconomic and neighborhood conditions exacerbate health problems. South Los Angeles residents don't have the ready access that wealthier communities do to healthful foods and safe parks. Generational poverty, lack of education and homelessness are prevalent.

"For many of the people in this population, health sometimes takes a back burner on their priority list," said Dr. Derrick Butler, a family physician and associate medical director at the clinic. "There are always competing priorities here."

To help patients manage their health, T.H.E. Clinic offers a nutritionist, a social worker, family planning counseling, diabetes classes and HIV support groups.

With the economic slump, T.H.E. Clinic already has seen a more than 50% increase in patients to nearly 12,500 since 2008, said President and Chief Executive Officer Rise Phillips. The number is expected to grow by an additional 25% next year.

Doctors, nurse practitioners and other care providers are expected to see about 25 patients each day, many with multiple chronic illnesses such as diabetes, hypertension and asthma. They race between patients as backlogs grow.

Some patients are willing to wait if they can regularly see a doctor they like.

Meredith Booker, with shiny hoop earrings and a worried expression, waited about 2 1/2 hours to see Butler one morning. Booker, 47, has migraines, depression and high blood pressure, problems that got worse eight years ago, after her 20-year-old daughter was killed.

"I like this doctor," she said. "He cares about his patients."

Butler, who has worked in community clinics a dozen years, tries to make his patients comfortable, chatting with them as peers. He was raised by a single mother in a poor neighborhood in Portland, Ore. "I understand this community," he said.

Opening the door to a bright, clean exam room, he greets Debra Greene, 52, a regular with dyed red hair and fashionably ripped jeans who takes more than 20 medications a day. She ticks off her illnesses for a visitor. Hypertension. Hypothyroidism. Endometriosis. Pulmonary hypertension. Allergies.