If an article is a few years old, but relevant to your topic, it can be very helpful to see who has cited it. This might be to see if the original research has been expanded upon or updated, or how it has been received. There are several different ways to do this, and the results will overlap -- no single method is comprehensive.
ISI Web of Science contains the Social Science Citation Index which allows you to do a "Cited Reference" search. This shows other articles (from a prestigious list of peer reviewed journals) which have cited the target article, and it also shows the references for the the original article... both forward and backward citation.
Google Scholar also provides forward citations for some articles. It has a broader range of documents included (not just peer reviewed journals, but reports, pre-prints, etc.) and doesn't eliminate self citation or de-duplicate the results.
CSA Illumina Databases sometimes provides Cited References for articles indexed in the CSA databases such as Social Services Abstracts, ERIC, EconLit, PsycInfo, etc.
For this class, we are going to use the following citation as an example:
Stone, S. (2007). Child maltreatment, out-of-home placement and academic vulnerability: A fifteen-year review of evidence and future directions. Children and Youth Services Review, 29(2), 139-161.
Full-text Access: Some fulltext UC dissertations (after 1996) can be found online by searching Dissertations & Theses @ University of California which also finds citations and abstracts for some UC dissertations prior to 1996. Berkeley dissertations prior to 1996 (in print) may be found by searching the Library catalogs. Dissertations done at other UC campuses prior to 1996 or ouside the UC system must be obtained through Interlibrary Loan or using the "Request" option in Melvyl. (NOTE: most dissertations can't be borrowed. If there is one you must have, contact your librarian about whether it's possible to buy a copy for our library.)