Multi-establishment firms account for around 60% of U.S. workers’ primary employers, providing ample opportunity for workers to change their work location without changing their employer. Using U.S. matched employer-employee data, this paper analyzes workers’ access to and use of such between-establishment job transitions, and estimates the effect on workers’ earnings growth of greater access, as measured by proximity of employment at other within-firm establishments. While establishment transitions are not perfectly observed, we estimate that within-firm establishment transitions account for 7.8% percent of all job transitions and 18.2% of transitions originating from the largest firms. Using variation in worker’s establishment locations within their firms’ establishment network, we show that having a greater share of the firm’s jobs in nearby establishments generates meaningful increases in workers’ earnings: a worker at the 90th percentile of earnings gains from more proximate within-firm job opportunities can expect to enjoy 2% higher average earnings over the following five years than a worker at the 10th percentile with the same baseline earnings.