The present study investigated the changes in Japanese students English writing behaviors over a 3.5-year period using multiple data sources including written texts, videotaped writing behaviors, and stimulated-recall protocols. Data from student interviews supplemented the analyses. Because 6 (henceforth, English as a second language [ESL] students) out of the 11 participants spent 2 to 8 months in English-speaking environments, the study was also able to examine the effects of such overseas experiences. The results revealed that over the observation period (a) both the English as a foreign language (EFL, remaining in Japan) and the ESL students improved their English proficiency, English composition quality-fluency, and confidence in English writing; (b) the ESL students overseas experiences were helpful for improving their writing strategy use and motivation to write better compositions; and (c) neither group's abilities or skills became like those of the EFL experts studied in Sasaki (2002).