A NEW YORK-BASED FILMMAKER of Hungarian, Chinese, and Brazilian descent, Elizabeth Chai Vasarhelyi spent five years on Youssou N'Dour: I Bring What I Love. Her first solo documentary, the film is a portrait of the great Senegalese singer as he released and promoted Egypt, an album in praise of Sufi Islam and 19th-century Senegalese religious leader Cheik Ahmadou Bamba, founder of Mouridism. Although N'Dour has a strong following in Europe and North America, he feared the album would be controversial in the West. Instead, it was spurned in his homeland, where longtime fans reflexively rejected a pop star's attempt at devotional music. Vasarhelyi's documentary, which observes this storm, has proved a success in Holland, France, and a few American cities, and opened Friday at the Avalon. In a recent interview, the director explained why she felt compelled to make the film, even though when she started she didn't know Youssou N'Dour's music.

I knew that I wanted to make a film about music in Africa. I felt that was a place to start. I discovered Youssou, and I thought he was an amazing musician. But I still wasn't sure if this was the right type of story for me to tell. When he shared the Egypt album with me, I knew. I thought what he was doing with the album, presenting a tolerant face of Islam, was critically important.

Also, it was unclear what would happen. Youssou was a very important artist at a turning point in his life, but I didn't know how this project would play out. I felt that the film could capture that in the making.

When did he share Egypt with you?

It was the second time we met, in Spain. We had met first at Carnegie Hall. I knew he was playing in Spain, and I snuck backstage, and he remembered me. And he burned me a copy of the album, from his brother's laptop. I had already heard about the project through one of his managers.

I was in Spain on my way to Kosovo, for a screening of my previous film. And I just dropped in on him. The best way to find Youssou is just to find him, and talk your way in.

After N'Dour recorded Egypt, it was delayed for several years.

The album was originally to be released in 2001. And then 9/11 happened. So he held it. The album was released in Senegal in the beginning of 2005. It was released in the West a few months later. And he began touring very shortly after the release.

How long did you film?

I filmed over two years. The film took five years to make. I lived in Senegal, filming and traveling with Youssou, for about two years. And we would go back into the field for certain big events. It took a long time to edit as well.

How did you choose when to film him outside Senegal?

The Fez Festival [of Sacred Music, in Morocco] was when he actually debuted the music. That was the first time I shot him. Then when he decided to tour Egypt in Europe. It was first time on the road without Super Etoile de Dakar [his longtime band]. He met the Egyptian musicians, who were most of the band, for the first time in Fez. Because they had recorded remotely.

At Fez it was very well received, but Youssou was so nervous. I only realized this afterwards. You see that in the footage. But I hadn't spent enough time with him to know that he was nervous. He normally is very much not.

With the Egypt album, there was always this feeling of new encounters. It was a new experience for Youssou, and that's kind of rare in his career. He's been around for about 30 years. I felt like there was something very vulnerable about that.

So I followed that first tour. As you see from that scene in Dublin [when N'Dour asked the venue not to serve alcohol], everyday was a new negotiation of how to handle the sacred music, and how the Egyptians and the Senegalese got along, and how the audience was reacting. Because no one knew.

In Senegal, after the controversy began, it was unclear what would happen. So it gave me the opportunity to spend much more time in Senegal, and get to know his family, and to get to know him personally better.

Was N'Dour surprised that album wasn't controversial overseas?

I think he was. You see in the film that the audiences really respond. But it was unknown if that would happen. Before Fez, he really didn't know how the audience would respond. Every step on the way in Europe, it was unknown. Who knew if the Dublin crowd would get upset about the ban on alcohol? It's a pretty tall order to ask the Irish to stop drinking.

The last show was in Amsterdam, and it was the same week that filmmaker Theo van Gogh was killed [by a Muslim extremist]. It was during Ramadan, and the city was on the brink. It was a very tense time there. And it was one of the best shows they ever did.

How were you received when you went to Touba, site of Senegal's largest mosque, for the annual pilgrimage?

The first time, Youssou was in the middle of the controversy. And he said, "You go. Figure it out. Do not mention my name. Discover it for yourself."

I thought we were going to come back that night. I had heard about what a big pilgrimage it was, but Touba's only about two hours from Dakar. We didn't come back for a week. [laughs] For the Touba pilgrimage, I'm grateful that we had that opportunity to go in on our own. To experience it for ourselves without mentioning Youssou's name.

I was never associated with Youssou, and so I wasn't received in his light. We had these ways of coordinating where we'd meet Youssou there. It was very tricky. It was a minority that publicly threatened Youssou; it wasn't the head of Touba. But it was a powerful minority. Senegal is a secular country, so they threatened to sue him in the courts [for impugning the memory of Cheik Ahmadou Bamba]. They didn't, but it was front-page news everywhere.

There were so many rumors. I remember when the Egypt cassettes were returned [from stores] overnight. No one spoke about it. It just happened. When the television stations pulled the commercials for the album, no one called to say it would happen. It wasn't that there was a fatwah against Youssou, or death threats. But it was such a taboo subject that no one supported him.

Were you considered interlopers in Touba?

People would be very curious about us. They would ask if I'm a Muslim, and I would explain that I'm not. And then they'd ask, "Why are you here?" And I would say that I think Mouridism is very interesting, and that people need to know about this. And they agreed. Senegalese Sufi Islam is a truly pacifist form of Islam, and very little is known about it in the West.

I was definitely the only Asian-American woman there. We all wore traditional dress, the whole crew. My principal cinematographer, Scott Duncan, is the brother of Tim Duncan, from the San Antonio Spurs. He's this huge guy, with these great dreadlocks. So he looks like a Baye Fall, which is one part of the [Mouride] brotherhood.

By the second time, people really respected that we came back and were committed to trying to understand. And that's when we got that amazing access to the mosque. That access was unprecedented. By the third time, I had my own bedroom in the culture ministry in Touba.

How big a crew did you use?

When I was on the road with Youssou, there were just two of us, myself and a cinematographer. I do sound. I even did the live musical recordings. In Touba, we were a bigger crew because we needed security. By the last time, we had three cameras. We had one Senegalese cinematographer and two American cinematographers, and they each had a Senegalese audio technician with them. That really worked.

But money was always the big issue. All the talent on the film was very much donated. The first trip to Touba was my first shoot with Scott Duncan, and he shot most of the rest of the film after that experience. He's won 14 Emmys. This was a passion project for everyone involved.

The film shows how the perception of Egypt in Senegal shifted after the album won a Grammy. But had anyone heard of a Grammy before N'Dour won?

No one had any idea what a Grammy was. Kabou Guèye, his composer, turned to me the day they won, and said, "What is a Grammy?" The way I tried to explain it was that it's like winning an Olympic gold medal. It was the first time a major international honor had been received by a Senegalese national, and that was newsworthy.

It was this Grammy award that forced a recontextualization of the album itself. It caused journalists to ask, "What's the big deal here?" Because when people listened to the album, they realized it does exactly what it set out to do, which is just celebrate these stories.

I never saw that coming, that the Grammy would have such consequences in Senegal.

Youssou N'Dour: I Bring What I Love — 2008, 102 min; at Avalon Theater.