The Tourist or Expatriot as Invited Guest to a Mexican Mass in a Church
Tourists vacationing in Mexico, and to a lesser extent expat residents in the country, can generally "get away with" wearing what they like. The issue is whether you want to be considered a gringo who doesn't know any better, or respected as someone who is making a conscious effort to fit in and be sensitive the particular cultural norms.
In most cases anything goes, even for foreigners. However, shorts for both sexes and sandals for men should be shunned. Otherwise, just know the location where the church is, and something about the family asking you to attend mass.
Class of the Family Extending the Church Invitation in Mexico
In first world countries generally class is a combination of culture and financial resources. The middle class in Canada, for example, has middle class values and lifestyle, and income. On the other hand, at least in certain parts of a developing nation such as Mexico, the state of Oaxaca as an example, one's material wealth does not necessarily mean that one lives a middle class lifestyle. A family can be monetarily upwardly mobile and thus be deemed by Canadian and American standards middle or upper class or somewhere in between, but culturally it may be what we might (ethnocentrically) consider working or within the lower classes. Be cognizant of the difference, if there is one, before dressing for a church mass.
For the upper classes in Mexico, culture more so than material wealth will dictate their dress and what they expect of invitees at urban and rural church services. For men, trousers and a cotton collared shirt is the minimum, and completely acceptable without a jacket and tie. Many Oaxacan men, for example, wear either a guayabera, or a shirt, usually without a tie, with a windbreaker. A jacket and tie is rarely if ever required or expected at a mass. For women, pants, a dress or a skirt are all acceptable, and tops can be strapless or sleeveless, with or without a shawl.
For Mexican church services sponsored by families who have significant financial resources but are not seemingly middle or upper class by Western cultural standards, dress is the same for both urban and rural functions, as for attending mass in small cities, towns and villages regardless of the culture of the family.
The Small Mexican City, Town and Village Church Environment as a Determinant of Dress
Let's start with the exception. In some cases, culturally and financially upper middle and upper class families celebrate rites of passage in semi-urban and rural locales. In such instances the minimum dress for men is trousers or finer blue jeans. A suit and tie is still not required. For women there is no difference between attending mass here, and in an urban setting at a function held by the culturally upwardly mobile classes.
In most cases, however, when attending church in a small city, town or village, regardless of monetary or cultural class, the most important piece of advice which can be provided is to not overdress. Since there will usually be attendees of modest financial means and of campesino culture, in reality anything goes for the locals, including regular jeans and T-shirts for men and skirt, dress or jeans for women. Younger women frequently attend church services in jeans, while women in their twenties and older tend to shed their jeans in favor of a dress or skirt. Regional clothing is often worn by women of all ages.
For foreigners, no ties for men and more muted attire for women is a good rule to follow. While regular blue jeans for both sexes is certainly acceptable, it is suggested that non - Mexicans attending this type of church service will themselves feel more comfortable not wearing "jeans and a T-shirt."
While the foregoing is intended to provide guidance for foreigners attending church services in Mexico, the best advice is to simply ask your Mexican hosts what's appropriate to wear. And in all cases, if your invitation includes being honored with being a godparent, dress up two notches, for men meaning consider that tie or a guayabera, and a dress or skirt for women.
Alvin Starkman and his wife Arlene operate Casa Machaya Oaxaca Bed & Breakfast. The Starkmans have been attending church services in both urban and rural Oaxaca on a regular basis for in excess of 20 years. Alvin writes articles about life and cultural traditions in Oaxaca, and helps visitors to plan their vacations in the state.