Writing in a second/foreign (L2) language imposes great demands on a writer due to the cognitive and social complexities it involves. In addition, such psychological variables as motivation and anxiety are highly likely to be related to success in L2 writing. So far, however, L2 writing has seldom been studied in relation to motivation and anxiety. Therefore, the current research investigated relations among achievement in L2 writing, anxiety, and such motivational constructs as self-efficacy, affect, beliefs, and goals for writing. A battery of questionnaires was administered to first-year English-major students at a state university in Turkey. Results indicated that success in L2 writing relates to higher confidence, decreased anxiety, positive feelings towards writing, and the desire to master L2 writing. Furthermore, the majority of the motivational factors and anxiety demonstrated significant intercorrelations ranging from a small to a high level. These findings yielded significant insights into the relations among success in L2 writing, writing motivation, and anxiety, which can be used to improve the quality of writing practices and pedagogical decisions.