Code-switching is a linguistic phenomenon that is often studied in the areas of contact linguistics, language education, and bilingualism. Most often code-switching has been studied in oral communication because most often those who code-switch use this linguistic tool in more informal settings. This paper analyzes code-switching in the context of Internet blogs. While the medium of blogging is a written one, it is a very informal setting and bloggers often use language that is more like speech than writing. For this reason, it is of interest to study code-switching in this area. In the present study, 20 Puerto Rican blogs are analyzed to examine the contact between English and Spanish in the language of the bloggers. The three hypotheses formed for this thesis are that 1) it is possible to propose a set of categories of code-switching that better describes and accounts for the data in Spanish-English Internet blogs; 2) most bloggers will use Spanish as a Matrix Language (ML) and English as an Embedded Language (EL); and 3) the most frequently occurring type of code-switch is lexical item switches. An additional goal of this thesis is to elucidate the differences between code-switching and borrowing in light of the fact that phonology can no longer play a part in the determination.