Diagnostic classification models (DCMs) have recently become very popular both for research purposes and for real testing endeavors for student assessment. A plethora of DCM models give researchers and practitioners a wide range of options for student diagnosis and classification. One intriguing option that some DCM models offer is the possibility of examining the nature of the interactions among the attributes underlying a skill. Attributes in second/foreign language (L2) may interact with each other in a compensatory/non-compensatory manner. Subskill/attribute relationship has been studied using diagnostic classification models. The present study provides a mini review of the DCM studies on the attribute relationships in L2 reading, listening, and writing. The criteria based on which interaction between the attributes have been inferred are reviewed. The results showed that the majority of DCM studies have investigated reading comprehension and more studies are required on the productive skills of writing and speaking. Furthermore, suggestions for future studies are provided.