Although the effects of test disengagement on the validity of the scores obtained from the data set have been examined in many studies, the predictors of the disengaged behaviors received relatively limited scholarly attention in low-stakes assessment, in particular, in international comparison studies. As such, the present study with a twofold purpose sets out to determine the best fitted explanatory item response theory model and examine the predictors of test disengagement. The data were collected by using items measuring literacy and numeracy skills of adults from different countries such as Norway, Austria, Ireland, France, Denmark, Germany, and Finland participated in PIAAC 2012. The results of the model with item and person characteristics demonstrated that adults tended to be disengaged on very difficult items. Similarly, age has a negative effect on test-taking engagement for adults in several countries such as France and Ireland, while several predictors such as educational attainment, readiness to learn, and the use of ICT skills at home and work had positive effects on test engagement. In addition, females exhibit a higher level of engagement in Norway. Overall, the findings suggested that the effect of the predictors on disengagement depended on the domain and country. So, this study brings further attention that the role of test disengagement should be a prerequisite practice before reaching a conclusion from international largestake assessments.