The purpose of this research is to 1) determine the influence of the principal's leadership as supervisor on teacher performance at SMA Negeri 1 Sipoholon in 2024; 2) Knowing the influence of teacher work motivation on teacher performance at SMA Negeri 1 Sipoholon in 2024; 3) Knowing the influence of the Principal's Leadership as a Supervisor and Teacher Work Motivation Simultaneously on Teacher Performance at SMA Negeri 1 Sipoholon in 2024. With the hypothesis: 1) There is a positive influence of the Principal's Leadership as a Supervisor on Teacher Performance at SMA Negeri 1 Sipoholon in 2024 2 ) There is a positive influence of Teacher Work Motivation on Teacher Performance at SMA Negeri 1 Sipoholon in 2024. 3) There is a positive influence of Principal Leadership as Supervisor and Teacher Work Motivation simultaneously on Performance at SMA Negeri 1 Sipoholon in 2024. The method in this research is a quantitative method with a descriptive statistical approach. The population is all teachers at SMA Negeri 1 Sipoholon, totaling 41 people and this research is a population study. Data were collected using a closed questionnaire with 60 reliable items, with rh>rt α 0.05 for all items and r11:0.90%. The results of data analysis show that there is an influence: 1) Leadership of the Principal as Supervisor at 37.2%, > 0, thus there is a positive influence of Leadership of the Principal as Supervisor on Teacher Performance at SMA Negeri 1 Sipoholon in 2024. 2) Teacher Work Motivation Regarding Teacher Performance, it is 23.8% > 0, thus there is a positive influence of Teacher Work Motivation on Teacher Performance at SMA Negeri 1 Sipoholon in 2024. 3) Leadership of the Principal as Supervisor and Teacher Work Motivation is 41.3% > 0, thus The positive influence of the Principal's Leadership as a Supervisor and Teacher Work Motivation simultaneously on Performance can be found at SMA Negeri 1 Sipoholon in 2024. In conclusion, Ha is accepted and H0 is rejected.