This study reports on Thai preservice teachers' appropriate Internet use behavior (AIUB) in 30 tertiary institutions across Thailand. The sample used both multistage random sampling and stratified random sampling to select the study's 1,800 participants which were grouped into two academic disciplines related to information and communications technology (ICT) and non-ICT disciplines. A questionnaire was used to identify both the internal and external factors, in which item reliability was judged to be 0.83-0.92. The HLM 7 software program was used to analyze the two-tiered linear model on pre-service teacher AIUB. Three types of two-tier models were evaluated, one with a dependent variable, a second model with student-level independent variables, and a third model using independent variables at both the student level and the school level. Data were analyzed employing average statistics ([x-bar]) and standard deviation using IBM SPSS Version 21 software. The HLM 7 software was used for the analysis of the three HLMs classified by ICT and non-ICT disciplines. Results revealed that each preservice teacher's abilities, characteristics, home/family situation, and their friends/classmates were predictive parameters that influenced the models, confirming the importance of these four variables in positively influencing preservice teacher AIUB.