We will be travelling in both Spain and Portugal in the fall. I have most of the connections figured out except for the one from Seville to Lagos, in the Algarve. Does anyone know if there is a train connection between the two places? Bus? A combination? We will be travelling on a Saturday, just to complicate matters!! Thanks. Carole

We caught a bus from Seville to Tavira, stayed there a night, and then caught the train to Lagos stopping off at a few other places along the way. Beautiful trip :-)
On a Saturday, go from Sevilla to Ayamonte (spanish border, either Sevilla-Huelva by train, then by bus or Sevilla-Ayamonte by bus directly), cross the River Guadiana by boat to Vila Real de Santo Antonio, then continue by train to Lagos. Check Damas (link above with tony_b) for bus timetables, “transportes publicos” (bottom of page) on ayamonte.org for boat services (they are frequent, no worry) and cp.pt for train timetables in Portugal (english version, too).
If I’ve read correctly, the trip can be done on a Saturday without any hassle: Bus from Sevilla-Ayamonte at 9.30, (unfortunatley they don’t show the duration of trip, but since it’s only 140km, it shouldn’t take too long), take a boat across the river around noon, get the 13.10 to Faro (arrival 14.18), change trains, spend two hours and continue at 16.17 to Lagos (arrival 17.55). There is an earlier train from Vila Real to Faro with less stopover, but it leaves already at 11.41 (arrival Lagos at 15.04), I don’t think you’ll catch it – anyway, you’ll have some time for the towns along the way.
;-)
Still, it takes a whole day for less than 300km… Personally, I wouldn’t mind that, I would even prefer this route to the direct bus. I was surprised myself that the trains Vila Real-Faro-Lagos run that frequently on a Saturday: One could even try to squeeze in a short stop in a place like Olhao, Loulé or Silves and take a later train to Lagos (but I don’t know whether the stations are always close to the city centre, and I’d guess that the lugagge would be bothering).

Thank you all! I am feeling better about being able to make this connection!!! Any and all suggestions will be welcome. What do you think about a few days in Lagos versus Faro? I hear that the beaches are nicer in Lagos, and there seems to be more there to do for a few days.
What about renting a car in Seville and driving to Lagos? Is crossing the border with a rental car a problem???

I messed that up. Correction:
ALSA bus to Faro: Saturday: 15:00 -16:30 , then train to Lagos: 18:12 -20:01

Henryk - is that an ALSA bus from Seville to Faro? That would be great!! If so, why does it take 7 hours to go from Seville to Lagos on the direct bus that runs m-friday?

There is no ALSA bus to Lagos. The ALSA bus shown is daily. It actually takes 2:30 hr due to the time change in Portugal. I took it from Lisbon to Seville. Here is the itinerary:
SEVILLA Est Plaza de Armas 15:00
HUELVA 16:15 16:15
AYAMONTE 16:30 16:30
VILA REAL ST ANTONIO 14:45 14:45 (Port. time)
TAVIRA 16:00 16:00
FARO 16:30 16:30
LOULE 16:45 16:45
FERREIRAS 17:00 17:00
GRANDOLA 19:15 19:15
SETUBAL 20:15 20:15
LISBOA ORIENTE 21:00 21:00
LISBOA SETE RIOS 21:15