This study examined the differences in jealousy expression between individuals involved in long-distance romantic relationships (LDRRs) and individuals in proximal romantic relationships (PRRs). Several of the variables that influence jealousy expression (ie, perceived threat, investment variables, and rumination) differ between long-distance and proximal romantic relationships, perhaps indicating that long-distance partners respond to jealousy in different ways than proximal partners. Quantitative and qualitative data were collected from 373 college students (104 in LDRRs; 269 in PRRs) to determine the links between these relationship factors and types of jealousy expression. Results indicated that while long-distance partners differed from their proximal counterparts on communication frequency and rumination, they did not differ on satisfaction, perceived alternatives, investment, commitment, or emotional dependency. Furthermore, individuals in these LDRRs and PRRs did not differ on their use of any type of jealousy expression. Numerous associations were found between investment variables (ie, satisfaction, alternatives, investment, commitment) and jealousy expression, as well as between rumination and jealousy expression. In support of some of the quantitative findings, analysis of the qualitative data uncovered five predominant categories of reasons participants gave for their use of various types of jealousy expression: perceived threat, investment variables, trust, long-distance relationship-specific reasons, and low self-esteem. The implications of these findings, the strengths and limitations of the current investigation, and suggestions for future research were also addressed.