This study highlights the significance of the integration of implicit-explicit vocabulary instruction, project-based learning (PBL), multimedia, and experiential learning to improve Thai EFL senior high school students' vocabulary ability. It aimed to investigate to what extent the integration affected Thai EFL senior high school students' vocabulary ability and how their perceptions toward the instruction were. The study involved 45 tenth-grade students at a public high school in Bangkok, Thailand. A vocabulary pre-and post-test was used to evaluate the students' vocabulary ability before and after the application of the integrated instruction. Additionally, students' reflective journals (SRJ), a students' perception questionnaire, and a semi-structured focus group interview provided qualitative data for analyzing the students' perceptions toward the instruction. The findings revealed that all students' test scores significantly improved and confirmed the effectiveness of the integrated instruction on vocabulary learning. All of the 45 students also reported positive perceptions toward the instruction. They reflected that the instruction was advantageous and practical since it facilitated their vocabulary learning, increased their selfconfidence and improved their speaking skills. It also created a pleasant learning atmosphere, provided the students with more opportunities to participate in classroom activities, and encouraged the students to learn with technology.

This study highlights the significance of the integration of implicit-explicit vocabulary instruction, project-based learning (PBL), multimedia, and experiential learning to improve Thai EFL senior high school students’ vocabulary ability. It aimed to investigate to what extent the integration affected Thai EFL senior high school students’ vocabulary ability and how their perceptions toward the instruction were. The study involved 45 tenth-grade students at a public high school in Bangkok, Thailand. A vocabulary pre- and post-test was used to evaluate the students’ vocabulary ability before and after the application of the integrated instruction. Additionally, students’ reflective journals (SRJ), a students’ perception questionnaire, and a semi-structured focus group interview provided qualitative data for analyzing the students’ perceptions toward the instruction. The findings revealed that all students’ test scores significantly improved and confirmed the effectiveness of the integrated instruction on vocabulary learning. All of the 45 students also reported positive perceptions toward the instruction. They reflected that the instruction was advantageous and practical since it facilitated their vocabulary learning, increased their self-confidence and improved their speaking skills. It also created a pleasant learning atmosphere, provided the students with more opportunities to participate in classroom activities, and encouraged the students to learn with technology.