It was time for this Texas family to get their tenses straight. So the four of them devoted a vacation to studying—and playing—at a language school in Mexico

In a recent evening in Guanajuato, a colonial city in the mountains of central Mexico, the mood was festive. Groups of competing mariachis—some in light-blue suits, others in the traditional black—sang at cafés lining the main park, with its Indian laurel trees trimmed square to resemble giant lamp shades. At one restaurant, Mexican vacationers were doing the samba between tables. On a bandstand, our two boys were playing hide-and-seek with local kids. At our table, however, my husband, Robb, and I were playing egghead. Books were open, and papers spread out between bottles of Los Indios beer. When the waiter delivered four plates of arrachera, grilled flank steak marinated in lime juice and garlic, we called the boys over.

"Necesitamos ... uh ... uh?" Robb began to say to a busboy as he made a stabbing gesture. "Tenedores," our eight-year-old, Gus, volunteered. "Cuchillo," Gus continued, holding up a knife. "Cuchara, papá," six-year-old Jeb chimed in, pointing to a spoon. My husband, with a slight roll of his eyes, dutifully wrote down the words in the vocabulary notebook he kept during our month in Guanajuato—a stay that was part vacation, part exercise session for the brain lobes that manage to juggle two grammar systems at once. This was our Mexico mission: to come, to see, to conjugate.

The four of us were enrolled at Academia Falcon, a language school for foreigners, in Spanish-immersion classes that met our level of expertise—or lack of it. Robb was a beginner. I was an intermediate whose ambition was to be able to watch a Pedro Almodóvar movie without subtitles. Gus and Jeb could already converse fairly well, thanks to their Spanish-speaking babysitter back in Texas. But this was their first experience in an all-Spanish all-the-time setting.

We chose to study in Guanajuato, population 140,000, over its famous neighbor, San Miguel de Allende, because there are fewer people from the States here—hence fewer temptations to fall back on English. But Guanajuato has other attractions, including a mummy museum and the Diego Rivera house, where you can trace the evolution of the muralist's style. The magnificent centro, designated a unesco World Heritage Site, is filled with 18th- and 19th-century buildings painted in sunset shades and decorated with ironwork balconies and door frames of green or gray cantera stone, mined and carved here. Winding cobblestone alleys climb the steep hills.

Our school was in one of the best neighborhoods, La Presa. With its steeply pitched roof, blue and gray stripes, and gingerbread flourishes, Falcon's main building looks like a Mexican version of a Swiss chalet. Behind this charming architectural aberration is a leafy campus with a modern four-story structure for classrooms.

Our lessons were in the morning. Robb was taking a "survival Spanish" course intended to help students avoid catching the wrong bus and coming off as Yankee yokels. He'd also signed up for a cooking class to learn to make dreamy tres leches cake (he is now required to practice for me at least once a month). My grammar classes—of no more than five students, mostly Americans like me who had some college Spanish—focused on verb tenses, including the wildly frustrating subjunctive form, and I also took a conversation course in which not a grunt of English was permitted. The boys' classes, for kids six to 12, were devoted to building vocabulary by playing hangman, singing songs, and creating stories to go with comic-strip drawings.

At around 8 a.m. every day, we made the 20-minute trek to school from our rental—a new two-bedroom, two-bath stucco house that we had lined up with the help of a study-abroad service—descending 238 stairs (the kids counted) along the way. We wound through parks where pink lilies grew and small children sipped aguas frescas (fruit juices) with their parents, and by vendors selling chilaquiles, a breakfast dish of tortilla chips, beans, and salsa.

At no point did our boys object to going to school. In fact, having the same student status as their parents made them giddy with the grown-upness of it all, and not a little full of themselves. "Mamá, dónde está tu clase próxima?" Gus once hollered across the campus from an upper balcony. Occasionally during their breaks, one of the boys, eager to buy a treat at the outdoor cafeteria, would poke his head into my class and say, "Necesito quince pesos for chocolate caliente." Ordinarily disturbances like these would have irritated me, but hearing my sons speak Spanish was such a joy, I would give them a pass—and the 15 pesos.

With afternoons free for exploring, we learned as much outside school as in it. When we got turned around in our car on our way to the silver mines in Valenciana, high above Guanajuato, Robb was forced to seek help at a gas station. He managed to get us back on track, winning my heart all over again (how can I not love a man who asks directions, even in Spanish?).

I had my own linguistic struggles. On a weekend excursion to the mining town of Pozos, about 1½ hours away, I went riding with Pepe, known in these parts as the Mexican horse whisperer. As we galloped across the agave-strewn countryside, I tried to make sense of his shouted Spanish instructions (so much for the whispering) while attempting to keep a feisty mare from having her Seabiscuit breakout moment. Just as I thought a fuse in my brain would fry, I finally digested his words (sit taller, heels down, thighs tighter) and was able to relish the ride.

Gus and Jeb fared better with their Spanish. I have often read that children learn foreign languages more quickly than their elders. In fact our boys seemed to pick up words and phrases effortlessly, forcing Robb and me to sometimes rely on them for translations. At a haunted house called Casa de Tía Aura—another of the tourist sites in Guanajuato—I didn't understand the tour guide's explanation of why the owner's niece had been murdered by her fiancé. Until Jeb filled me in (the fiancée loved someone else).

Utterly lacking in self-consciousness, the boys were always keen to speak in Spanish—to buy our tortillas at the local tortillería or the tickets for the cable car up to a monument on a hill overlooking the city. One evening outside the glorious Teatro Juárez downtown, where clowns entertain crowds on the steps, Gus offered to be part of the act, the only blonde head in the group of children singing a goofy Spanish song. I couldn't muster that kind of courage. But I did go over and chat with the parents of the kids our boys approached in the park for a game of soccer. I also visited the mother of nine-year-old Sergio, who lived next door to us and became a good friend. Sitting in her kitchen over a cup of tea, we talked about the challenges of raising boys and about what Spanish books she thought my kids should read—she even gave us some to take home.

We also brought back Spanish words and phrases that we use frequently. I say basta ya ("stop it") and vente ("come here") when I really want the boys to heed me. They tell me my ideas are loca. My husband—who has never forgotten the name of each table utensil—uses mijo, a merging of mi hijo, or "my son," when talking to one of the boys; sometimes he calls me mi amorcita, which has the same effect on me as Gomez Addams's French had on Mortitia. Our new vocabulary is surely the best souvenir we've ever picked up on a family vacation. ✚

Jeannie Ralston's memoir, The Unlikely Lavender Queen, will be out from Broadway Books this spring.

When and How to Go

Guanajuato is a year-round destination, known for warm days and crisp nights. It's a five-hour drive from Mexico City, but most visitors fly into the airport in nearby León, which has direct flights from the United States on American, Continental, Delta, and the major Mexican airlines.

Language Classes

Academia Falco (80 Paseo de la Presa; 52-473/731-0745; academia; week of three-hour classes, adults and children $85 per week). The school's Spanish-immersion programs are for all levels and meet in small groups. There are special courses for kids ages six to 12.

Where to Stay

Academia Falcon typically arranges for its students to bunk with local families. If you're looking for a rental house or hotel or want to organize outings in and around Guanajuato, El Quijote (52-473/ 731-0297; mexico, a study-abroad service, can help.

Quinta Las Acacias (168 Paseo de la Presa; 52-473/731-1517; quintalasa; doubles $200), a sumptuous hotel in a renovated 19th-century mansion, is located conveniently near the school.

Where to Eat

Posada Santa Fe A lively outdoor café in the main square serving grilled steak and Mexico's greatest hits. 4 Jardín Unión; 52-473/732-0084; lunch for four $50

Restaurante-Bar Café Los Agaves A school hangout with lovely Frida-Kahlo-inspired art and the best margaritas in Guanajuato. 91 Paseo de la Presa; 52-473/731-2882; dinner for four $25

What to See

El Museo de las Mommias A popular, albeit creepy, Guanajuato tourist site. My tour guide insisted that the mummies-some minerals in the soil here inexplicably mummify entombed bodies-had not been buried alive, despite rumors to the contrary. Fascinating, but too graphic for kids under 10. Explanada del Panteón Municipal, 52-473/732-0639;

Museo Casa Diego Rivera Boyhood home of the famous muralist featuring his paintings (including a look at his Cubist period) and a lithograph of Frida Kahlo, 47 Calle Positos; 52-473/732-1197;

Casa de Tía Aura. A "haunted" house with special effects. 62 Paseo de la Presa; 52-473-731-1824

Tram to "El Pípila" Skinny cars climb the hillside tracks to a gigantic monument to a revolutionary hero. Plaza Constancia, behind the Teatro Juárez

Museo Regional de Guanajuato de la Alhóndiga de Granaditas This old grainhouse was the site of the first major rebel victory in the War of Independence ,and is now an art and history museum. 6 Calle 28 de Septiembre; 52-473/732-1112

San Ramón Mineshaft A silver mine open for tours (find it behind the cathedral in Valenciana; 52-473/732-3551). The nearby Valenciana Mine has a small mining museum.

The Centro Bilingüe de San Miguel

The Centro Bilingüe de San Miguel sits among colonial mansions and lavish churches.

For Parents: The catalogue ranges from hourlong basic vocabulary to weeklong "Spanish Survival" courses.

For Kids: Separate days camps for grade-schoolers and teams-both groups go on field trips to historic sites and markets, and take cooking classes.

Getting ThereLeón/Guanajuato airport (110 miles away) or Mexico City international airport (170 miles away) 46 Correo, Centro, San Miguel de Allende, Guanajuato; 52-415/152-5400;; adult prgorams from $70 per week, children's and teen camps from $200 per week, private lessons, $20 per hour

Amigos del Sol

Amigos del Sol is in Oaxaca City, known for lovely zocalo where you can buy giant sparklers, and its historic sites-don't miss Monte Albán, one of the earliest cities in Mesoamerica.

For Parents: The one- to five-hour classes have a max of five students per session, and you can start any day of the week.

For Kids:Groups are divided by ability rather than age, so if you're all at the same level, you can study as a family.

Getting There Oaxaca international airport (10 miles away)109 Libres, Oaxaca; 52-951/514-3484;; from $90 per week (three hours of class time per day), private lessons, $12 per hour

Spanish Abroad

Spanish Abroad organizes programs at two schools in Puerto Vallarta.

For Parents: Weeklong programs only-but you can opt for a package that includes classes, rooms with a host family, meals, laundry service, airport pickup, cultural activities, and books-for the whole brood.

For Kids: The under-16 set has their own one-week sessions, and can sign up for private- or semi-private tutors.

Getting There: Licenciado Gustavo Díaz Ordaz International Airport (5 miles north of town).

Spanish Abroad; 888/722-7623;; weeklong program with host family accommodations, $350 for adults in group class, $410 for children (with semi-private instruction)

Spanish Abroad also has two posts in Playa del Carmen, on the Yucatán peninsula-so you can study and swim.

For Parents: As at its Puerto Vallarta locations, all-inclusive packages are available here (you can add on scuba diving and snorkeling), and parents' programs are separate from children's.

For Kids:You can schedule their courses to take place during adult class times.

Getting There: A driver from the school will pick your gang up at Cancun Airport International (40 miles away).

Spanish Abroad; 888/722-7623;; weeklong program with host family accommodations, $390 adults, $375 children; airport pickup $40 for the first person, $35 for each additional passenger.