Please remember that ejbs were designed to be very scalable. From here all these great concepts like instance pooling, cluster aware stubs, etc. Of course not all type of ejbs are highly scalable and an example could be the SFSBs. Some people would say that even entity ejbs are not what they were promised to be in the first place and they are only trouble. In my opinion one still can design a scalable system using entity ejbs, but s/he probably needs to employee vendor specific solutions. As for the SLSBs, the story is controversial again, since some people say that they are great, while other would argue that they are not worth the trouble. Finally there are the MDBs and here most of the people I know do agree that they are a very good choice. To answer to your question I�d say that at least in theory using ejbs will make your application scalable, because this was the reason for designing them in the first place. In practice I can tell you that you�ll never go wrong with MDBs and if you fallow a good design you can discover that SLSBs are a pretty good choice too. Entity ejbs on the other hand require an in-depth knowledge of the container and you have to sacrifice the portability (in practice this is just a utopia anyway) for scalability. As for SFSBs, unless you have rmi clients that need to maintain state information, you better stay away and use HttpSession instead. Regards.