Transferring at Gare St. Lazare

When you exit at the Saint Lazare stop on the metro, you need to exit the metro system and follow the signs for the "regular" train station (Gare St Lazare). Look for the signs in the station. The pictures here may help: https://parisbytrain.com/gare-saint-lazare-train-station-photo-guide/ Specifically, you need to follow the signs for the Transilien trains if you want Line J. You do not need the Grandes Lignes which are for long distance travel. Generally speaking, and of course there could be exceptions, tracks 1-9 serve the suburban trains (the Transiliens). The train station is built above the metro station and the metro station is on the lowest level. If you click on the Station Map at https://www.gares-sncf.com/fr/gare/frpsl/paris-saint-lazare, you will see a map of the station.

You did not ask for help with Chatelet-les-Halles but what street do you need to get to and what train are usually arriving on when you are get to the station? Chatelet-les-Halles can be confusing but there are some tips to make getting around easier.

I believe the "J" trains go from the main platform area where Grandes Lignes trains are. They have installed gates where you scan your ticket to access the platforms.

Yes the confusion is that “J” line trains don’t really have anything to do with the metro, they are trains to/from areas outside of Paris. In fact I think it a bit more confusing to think of such trains as the “J” line — you just need to get to the regular train station at Gare St Lazare when leaving the metro, and look for your train’ destination (also helpful to know the name of the last city for which your train is destined, as your train will be listed under that name — the interim towns will run in a running list below that final destination name.

As for exiting correctly at Châtelet, it definitely is confusing. You might try using the CityMapper app. It tells you what part of the metro train to be on for the direction you want to exit, and the name and number of the exit you need. Sometimes though the signage at Châtelet is so horrible you’re left stumbling around the corridors, and finally just have to get out SOMEwhere. Ugh.

We are at 17 rue Victoria and there is a Chatelet entrance literally at our door. We have yet to enter because we prefer to walk in the AM, perhaps if we did it would solve or dilemma!

The metro entrance at 17 avenue Victoria is really an outlying entrance for line 14. If you need line 14, walk to rue des Lavandières Sainte Opportunes; line 14 entrance is at the corner between that street and Rivoli.