Ho can I get from Boston to Baltimore?

You can use <a target=new class=ftalternatingbarlinklarge href="http://www.mapquest.com/directions/main.adp?go=1&do=nw&rmm=1&un=m&cl=EN&ct=NA&rsres=1&1ffi=&1l=&1g=&1pl=&1v=&1n=&2ffi=&2l=&2g=&2pl=&2v=&2n=&1pn=&1a=&1c=Boston&1s=MA&1z=&2pn=&2a=&2c=Baltimore&2s=MD&2z=&r=f">Mapquest</a> to find the distance, directions, and ideal driving time between two places. It says 406 miles and seven hours. Without a car you can use, planes, buses, trains, or a combination. We caught a Greyhound bus from New York to Baltimore and it was very easy.

See FAQ post 200: "Washington-Philadelphia-New York-Boston Via Public Transit" for ideas.

Take the train, bus, or plane to D.C. (if flying, to BWI) and then take the regional train to Baltimore. Plane is about 1.5 hours (flying time), train about 8.

The train is the most comfortable, but it's expensive. The Chinatown bus is the cheapest. It's pretty reliable. Google "Chinatown Bus" and you'll get a bunch of different company names.

You fly on Airtran, it is quite cheap ususally.

I'd take southwest to BWI usually

If you take a train, you can go direct to Baltimore, you don't have to go to DC. The train from Boston stops at BWI airport.
The flight is about an hour, often just under. But things between BOS and BWI are also often delayed.

Just curious, why do you want to go to Baltimore???

Anywhere to escape Boston.