This study was designed to examine nutrition label use, self-efficacy, snacking and eating behaviors of middle school students, and to investigate if these characteristics were different by nutrition label use. A cross-sectional survey was conducted to 348 middle school students in Kyunggi, Korea. About a third of subjects read nutrition labels when they purchased snacks/packaged foods. Most nutrition label users were interested in reading information on calories, fat and trans-fat. Self-efficacy of eating/selecting snacks or general nutrition behavior was moderate (mean score: 44.4 out of 60), with significantly higher score in nutrition label users compared to nonusers (p < 0.001). Nutrition label users felt more confident in 9 items out of 15 items of self-efficacy, such as "taking fruits instead of cookies/candy for snack" (p < 0.001), "choosing milk instead of soft drink" (p < 0.01), "not having snacks after dinner" and "avoiding processed foods for snacks" (p < 0.05). Subjects had snacks 1.3 times a day, and nutrition label nonusers consumed snacks more frequently than the counterparts (p < 0.01). About 55% of nutrition label users and 64.7% of nonusers mainly purchased snacks for themselves (p < 0.05). Commonly purchased snacks by adolescents were ice cream, cookies/chips, breads and ramen. Major considerations in purchasing snacks were taste (46.9%) and price (34.6%). In selecting snacks, the influence of friends and parents was greater than the other sources. Based on eating frequency of snacks, nutrition label users were more likely to consume healthy snacks, such as fruit juices, vegetables, milk, yogurt, and potato/sweet potato than nonusers (p < 0.05). Eating behaviors measured by 15 items scored 33.6 out of 45. Nutrition label users showed better eating behaviors, such as "eating meals slowly", "eating foods cooked with plant oil", and "eating out less frequently" (p < 0.05). Study results showed that majority of adolescents did not read nutrition labels, selected snacks for themselves and had somewhat unhealthy foods for snacks. This study also showed the differences in self-efficacy, snacking and eating behaviors between nutrition label users and nonusers. In nutrition education, it is necessary to stress the importance and skills for reading nutrition labels. It is also needed to help adolescents to select healthy snacks and have desirable eating behaviors, as well as increasing self-efficacy.