Practice is essential for improvement on any instrument, so music teachers must teach their students how to practice effectively. Effective practice involves many strategies, including focused repetition (Ericsson & Harwell, 2019), imitation of a model (Hewitt, 2001), and use of a metronome (Geringer et al., 2015). Researchers have found that mental practice has a positive effect on performance in some settings (Madeira & dos Santos, 2024) and is particularly beneficial when combined with physical practice (Miksza, 2005; Ross, 1985). Few scholars have investigated the effectiveness of mental practice strategies in string education.The purpose of this study is to examine the relative effectiveness of three practice modalities—physical practice, mental practice, and a hybrid of physical and mental practice—in enhancing performance outcomes among collegiate string players. Specific research questions include: (a) How do different practice methods—physical practice, mental practice, and a hybrid approach—affect performance outcomes among collegiate string players? and (b) What challenges do college string students experience during mental practice?Participants in this study (N = 45) include university violinists, violists, cellists, and bassists. Data collection is ongoing. Each participant is assigned to one of three treatment groups (physical, mental, or hybrid practice) for three 20-minute practice sessions on three consecutive days. The dependent variable, performance achievement, is being measured using the String Performance Rating Scale (SPRS; Zdzinski & Barnes, 2002) and an adaptation of the Farnum String Scale (FSS; Farnum, 1969). Two excerpts were adapted by the researchers from the FSS, and researchers are measuring individual pre- and post-test performances of each excerpt. The two researchers and one graduate student in string music education are scoring pre- and post-test recordings to establish reliability. Data will be analyzed using a one-way ANCOVA with pre-test scores as the covariate. After all three practice sessions are finished, each participant is completing a brief survey about the strategies they used and the challenges and benefits they experienced during practice sessions. The researchers are coding these responses for emergent themes.Results of this study may help string teachers better understand and incorporate mental practice in their teaching, potentially improving teaching effectiveness, practice effectiveness, and student learning outcomes. Results of this study may also help to address issues of equity, as students with limited access to practice space or an instrument outside of class may be able to employ metal practice strategies to continue skill development outside of formal lessons.