GUATEMALA CITY - The little boy flies like an airplane through the hotel, his arms outstretched. Then he leaps like a superhero, beaming as the red lights on his new sneakers flash, while the American couple he is with dissolve in laughter.

He calls them Mama and Papi. They call him Hijo -- Son. He corrects their fledgling Spanish. They teach him English. "Awe-some," he repeats carefully, eyeing his shoes.

To outsiders, they look like a family. But 6-year-old Geovany Archilla Rodas lives in an orphanage on the outskirts of this capital city. The Americans -- Amy and Rob Carr of Reno, Nev. -- live a world away. They are the only parents he has ever known.

They have been visiting him every year, usually twice a year, since he was a toddler, flying in for a few days at a time to buy him clothes and to read him stories, to wipe his tears and to tickle him until he collapses in giggles. Yet half a decade after agreeing to adopt him, the Carrs still have no idea when -- or if -- they will ever take Geovany home.

"There's this hope in you that doesn't want to die," said Amy Carr. "In my heart, he's my son."

The Carrs are among the 4,000 Americans who found themselves stuck in limbo when Guatemala shut down its international adoption program in January 2008 amid mounting evidence of corruption and child trafficking. Officials here and in Washington promised at the time to process the cases expeditiously.

But officials and prospective parents say that bureaucratic delays, lengthy investigations and casework hobbled by shortages of staff and resources have left hundreds of children stranded in institutions for years. Today, 150 children -- including Geovany -- are still waiting in orphanages and foster homes while the Guatemalan authorities weigh whether to approve their adoptions to U.S. families.

Stalled adoptions are not unique to Guatemala. Concerns about fraud, including allegations of kidnappings and baby selling, have held up U.S. adoptions for months, and sometimes years, from Ethiopia, Kyrgyzstan, Vietnam and Haiti. The State Department currently refuses to approve adoptions from Cambodia and Vietnam to pressure those countries to install safeguards so that children with biological relatives who can care for them are not sent overseas.

But the problem of delayed adoptions is particularly acute in Guatemala, a country of about 14 million people, which in 2007 ranked second only to China in the number of children sent to the United States.

As officials here have spent months, and then years, trying to distinguish legitimate adoptions from fraudulent ones, many hopeful couples who had painted nurseries and bought brand-new cribs began to despair as the infants they had hoped to adopt took their first steps and spoke their first words without them.

Faced with a seemingly endless process, scores of prospective parents quietly abandoned their adoption efforts.

Guatemalan officials said they never intended for the children to remain institutionalized for so long. They say they have had to thoroughly investigate the cases, some of which are complicated by inconsistencies, false documents and questionable stories, to ensure that the children were not bought or stolen from impoverished rural women.

"These are very vulnerable people, who can be easily taken advantage of," said Elizabeth Orrego de Llerena, president of the board of directors of the National Adoption Council, which is processing the adoption cases once they have been cleared by the child welfare investigative branch.

Orrego de Llerena said that the investigations, which typically include searches for biological relatives, were necessary to ensure that children were given up voluntarily.

U.S. officials counter that the process has taken long enough, saying that anomalies often reflect complicated family situations, not corruption, pointing to instances in which unmarried teenagers and victims of rape and incest have lied about their identities.

They say many judges and child welfare officials in Guatemala have delayed approving cases out of fear of increased government scrutiny.

"If no one, after all this time, has come forward to say I want to give this child a home, I think the matches they have made in the past should be honored," said Susan Jacobs, the State Department's special adviser for children's issues, who has traveled to Guatemala four times trying to resolve the backlog. "Just decide. Don't leave these kids forever in institutions. It's just wrong."