The purpose of this study is to investigate the influence of L1 on the quality of three different types of L2 writing products in the forms of direct writing (L2 writing task on a given topic), translated writing (L2 translation of L1 writing on the topic) and back-translated writing (L2 translation upon L1 translation of a short L2 text). Our aim was to identify explicit ways of enhancing L2 learners` writing ability by exploring writing tasks which involve different degrees of L1 use, ability and knowledge in producing and organizing the texts. We analyzed a total of 105 L2 writings of the three different tasks in terms of grammatical and discursive features. In order to understand how grammatical features of L2 writing are influenced by L1 in writing tasks, we assessed syntactic complexity and lexical density, accuracy in word choice, sentence structure and verb inflection. In addition, discursive features were evaluated by the scales of analytic scores, expression, and transition. Results indicated that L1 positively influences organization and vocabulary use in translated L2 writing, and also positively affects back-translated writing in terms of maintaining the original sentence structures.