Go to Bahn.de and try it. I got a train taking 5:43 with one connection--I assume Trieste.

Thanks, I just found the website ( RailEurope ) and it is possible to travel Ljubljana to Venice via Vilach.

Yes, but Raileurope is a commercial broker and you will pay more.

A Slovenian company called DRD runs a direct bus from Ljubljana to Mestre (then a ten minute train ride to Venice Santa Lucia). I took this bus the other way a few years ago (from Mestre to Ljubljana):

http://drd.si/en/

Probably a lot easier than the train connection in Austria.

I am planning a similar trip and just posted a question about getting from Trieste to Ljubljana and got a great response with links. Click my name to bring up the thread and then you can click on the links in the response to get the bus schedules. It looks like an easy two hour train ride between Venice and Trieste and apparently the train and bus terminals are right next to each other (if I'm reading the answers to these questions correctly on various threads). I personally wasn't planning on spending any time in Trieste but after reading some of the stuff here it looks like such a nice town I'm now planning on adding a day or two there. It's the logical connection point between Venice and Ljubljana.

In the near past at least there has been some disruptions in direct rail service between Slovenia and Triest with a bus link at times. But yes www.bahn.de, the German Railways pan-European train schedules is IMO the best source and easiest to use for any European train schedule - a good way to get to the bahn.de's English schedule page IME is to go to the home page of www.budgeteuropetravel.com and click on the link "Best Online European Train Schedule" (or some such wording) and this links you directly to the bahn.de English schedule page - I give this home page link because it also gives you several valuable tips on how to use the bahn.de site that may not be apparent at first encounter.

I just went on the bahn.de site and put in both Venice and Trieste as departures. It looks like from Trieste to Ljubljana it takes over five hours and a couple of changes, some of which involve a bus. Am I reading that right?

On the site given me by hkto when I asked the similar question (http://www.autostazionetrieste.it/index.php?option=com_content&task=view&id=15&Itemid=0 ) it gives a bus schedule with three buses a day each taking about two hours.

Why would anyone take the train - or am I not reading something right?

There is no direct train between Trieste (spelled "Trst" in Slovenian) and Ljubljana. There are only a few direct buses a day as you have found. Optionally, you can take a bus from Trieste to Koper, Slovenia (not Sundays or Italian holidays, though) and train from Koper to Ljubljana. Or take a taxi from Trieste up to Sezana, Slovenia (only about 14 km it appears) and then a train from there to Ljubljana.

If you want a scenic diversion between Trieste and Sezana, there's also a funicular/tram from Trieste up to Villa Opicina:

http://en.wikipedia.org/wiki/Opicina_Tramway

then you'd get a taxi from there on to Sezana. But of course, this will add more complication and time to the trip...

The Trieste bus station website you already found shows you the schedule of buses from Trieste to Koper and Trieste to Ljubljana. This site shows you Slovenian trains from Koper or Sezana to Ljubljana:

http://www.slo-zeleznice.si/en/