Does the Saturday Vigil Mass “count” only for certain reasons (e.g., healthcare worker who works on Sundays)? What if I just find Saturday 4PM more convenient than Sunday 10AM due to time and a particular parish is closer? (I’m going through RCIA in one parish, but I go to another parish for Mass that’s closer to work.)
No, you may choose to attend the Saturday evening mass as often as you like, without needing special circumstances. See canon law:
§1 The obligation of assisting at Mass is satisfied wherever Mass is celebrated in a Catholic rite either on a holy day itself or on the evening of the previous day (canon 1248, Code of Canon Law).
However, you might not be aware that even though you went to mass on a Saturday evening, you must still keep the Lord’s Day. You do that on Sunday itself, subject to constraints of your ability, of course.
No, it is the Sunday Mass and fulfills the obligation any time you attend.
That is totally fine.
The only potential problem I see involves RCIA, since there are rites for RCIA candidates that are done at Mass on Sunday, and the dismissals/scrutinies in Lent.
And as has been explained before, the “Vigil Mass” on Saturday evening is not a “vigil” but is the actual Sunday Mass itself, with the same readings, etc.
Only a very few feasts have an actual “vigil” with different propers and readings for the previous evening versus the feast day itself.
The moderators should consider having a sticky on this topic. It keeps coming up time and again.
Also may be a wedding Mass or Funeral Mass, etc., may meet the obligation and have different readings, at a time after Saturday Noon. The time was relaxed with the 1983 canon law (the sense is afternoon).
The Canon Law: Letter & Spirit, Canon Law Society of Great Britain and Ireland, 1995 has:
What is “the evening of the previous day”? Despite the view of some commentators that this should be interpreted as beginning only at 1400 hours (2 PM) on that day, it is the firm view of this commentary that the evening of the previous day begins at midday (12 noon) on that day itself. In some dioceses there is a local regulation to the effect that the so-called vigil or anticipated Mass may not be celebrated before, say 5 or 6 PM…
Those regulations do not in any way concern the time prescribed for fulfilling the obligation to assist at Mass: thus e.g. if in such a diocese a person were to attend a nuptial Mass in the early afternoon on Saturday, that person would have fulfilled the obligation … of this canon 
It’s been the canon law of the Church since 1983.
It’s frustrating (to me, as a priest) that
- this has been explained so inadequately
- some people just insist on imposing the outdated law (that one needs a reason) for their own personal reasons
It’s not CAF that needs a sticky. The Church needs one.
The fact that people on CAF keep asking it is an indication that there’s a real problem out there. After 31 years, the outdated law is still being taught.
I think you will get different answers from different people, even from different priests. The original intention for the vigil Mass, as you stated, was to help people like firefighters, police officers, etc., who cannot make it to Mass on Sundays for legitimate reasons, to be able to make it to Mass. Over the years, it has evolved into its current form. When I was going through RCIA, I was told that it’s fine to go to vigil Mass instead of on Sunday. To be honest, I’ve always felt weird going to Sunday Mass on a Saturday, but have done so on many occasions due to its convenience. But then again, Mass is not about our convenience, and for those of us who can make it to Mass on Sunday, I honestly don’t see a reason why we shouldn’t make an effort to do so.
Also, as a side note, there are no vigil Traditional Latin Masses offered on Saturdays, which are on Sundays only. I may get quite a bit of flak for saying this, but a novus ordo priest is more likely to tell you it’s okay; whereas a traditional priest will more likely tell you that you should make it to Mass on Sundays if you can.
I feel a bit weird as well, but part of the reason is convenience and the other part is that the Saturday Mass has less people — I just find that I get less distracted when there are less people around. It seems to be a bit more quiet to get in a quick prayer before Mass, and the average age is older. I feel less anxious around older people for some reason.
Or maybe it’s just an excuse for being anti-social.
Not really. Many like to sit in first-class, where it’s not so crowded.
This isn’t about personal opinions. The Church tells us that it makes no difference. The Mass on Saturday evening is still the Sunday Mass.
Before the 1983 Code of Canon Law, there was a requirement that a person needed a good reason to attend on Saturday evening instead of Sunday. That law no longer exists, and the requirement of a reason no longer exists.
An individual person says that Mass after Noon fulfills the Sunday obligation.
The Code of Canon Law says differently. Only a Mass in the evening (Latin vespere which means roughly 4 PM) fulfills the obligation.
One who attends Mass on Saturday early afternoon has not fulfilled the obligation of canon 1248.
I feel that way sometimes, too, when I go on Saturday.
There are times I go on Saturday when I could go on Sunday, as this week, but I also like to listen to the EWTN Mass on Sunday morning on EWTN radio in my town. I feel that I get something out of that and I don’t feel that I’m doing anything wrong.