<p>In the fields that I know, there are some strong researchers at LACs, but a very limited number. It is difficult for them to get a critical mass of researchers, to get big grants, etc. This does not mean that students at an LAC cannot get involved in research projects that prepare them well for graduate school, but the top researchers are unlikely to be there. Those who choose to go to LACs typically go there because they want to teach well and know that this will be a fair amount of work (or because they couldn't get a good enough job at a research university). At a research university, quality of teaching typically gets modest rewards if any whereas quantity/quality of education is highly rewarded. So, the people who go there preselect for an stronger emphasis on research and then the institutional incentives drive them further in that direction. Undergraduates who are able to get involved in the research can get in on cutting edge stuff. I did. But you may have to be more impressive to your professors to get involved than you would at an LAC because they don't have the grad students there.</p>
<p>I am sure there are some pockets in LACs with high quality research. There are certainly schools that produce a lot of undergraduates who go on to Ph.Ds. But if being on the cutting edge matters, you would likely not want to be at an LAC. In my case, I worked for one of the leading people in my field as a research assistant as an undergraduate and then he served as my thesis advisor. My undergraduate thesis was published in the leading journal in the field and in graduate school, I was told by one of the luminaries of the Harvard department that it would have been the best Ph.D. theses in the department at Harvard for the last 5-10 years. [This made getting through graduate school successfully a lot easier]. It would be very unlikely to have that experience at an LAC as I wouldn't have had access to the equivalent of my undergraduate adviser. </p>
<p>But, in my graduate school department, we had a very strong kid who had gone to Hampshire and really knew how to do research independently. He learned very well from a professor who was not a stellar researcher but was a good teacher. There are lots of ways to get a good education.</p>