Abstract : The implementation of Jumantik 1 House 1 Movement (G1R1J) is one of the DHF transmission prevention programs that involves the active role of the community, especially family members, to eradicate mosquito nests both inside and outside the home. The purpose of this study was to see the effect of G1R1J's knowledge and actions on larval density before and after the intervention. The research design was quasi-experimental with Non-Randomized One Group Pretest-Posttest with Control, namely the experimental group that received treatment and the control group as a comparison. The results showed that the results of data analysis using the Friedman Test obtained: Asymp value. Sig of 0.000. If the Asymp. Sig. <0.05, there is a decrease in the value of larval density in each observation before and after the G1R1J socialization intervention. The influence of knowledge and actions of G1R1J on larval density using the Chi-square test obtained a Sig value of 0.000. If the Sig value < 0.05 then there is an effect of the knowledge and actions of the respondents about G1R1J on the density of the larvae. Suggestions for assistance to the community need to be carried out periodically so that PSN activities are routinely carried out.