The purposes of this study were to validate the writing section of the Eiken Can-Do Questionnaires used in this study and the second purpose was to determine the effects of ten affective orientations (i.e., Desire to Write English, Attitude Toward Learning to Write English, Motivational Intensity, Instrumental Orientation for Writing in English, L2 Writing Anxiety, L2 Writing Self-Confidence, Willingness to Communicate in L2 Writing, Self-Esteem, Cognitive Competence, and General Self-Worth), on the participants’ responses to the Eiken Can-Do Questionnaires. This purpose is valuable because little is known about the relationship between Can-Do Questionnaire and affective variables investigated in this study. The final purpose of this study was to develop Can-Do Questionnaires as an internal measure for a university writing class. The participants of this study were 204 university students studying in two private universities in Tokyo, Japan. The first instrument was the writing section of the Eiken Can-Do Questionnaire; this questionnaire served as the outside measure in this study. The second, six out of nine essays written by the students were assessed as a measure of their writing ability in English. The Affective Orientation Questionnaire was administered to measure ten Affective Orientations. The questionnaire and essay data were analyzed using the Rasch rating scale. All of the participants completed the Background Questionnaire and Affective Orientation Questionnaire in April 2010 and 2011 and completed the writing section of the Eiken Can-do Questionnaire in April, July, and December 2010 and 2011. six writing assignments were produced by 179 out of the 204 participants wrote during the 2010 and 2011 academic year, and the relationships among the variables were analyzed using Structural Equation Modeling. The results indicated that the use of the Eiken Can-Do Questionnaires as the proficiency level measure was appropriate for this group of university students. The Eiken Can-Do Questionnaires were predictors of Motivation and L2 Self-Confidence. Motivation was a predictor of WTC in L2 Writing. Therefore, it should be noted that the Eiken Can-Do Questionnaires had an indirect effect with WTC in L2 Writing. The result implies that through having Eiken Can-Do questionnaires and Classroom Can-do Questionnaires to achieve their future goals, their English classes and their future learning objectives were connected.　 It is necessary to provide students with adequate practice and guidance in using the Eiken Can-Do Questionnaires in order to promote a deeper understanding of their purposes and uses. / Teaching & Learning