Calcium imaging using GCaMP calcium indicators and miniature microscopes has been used to image cellular populations during long timescales and in different task phases, as well as to determine neuronal circuit topology and organization. Because the hippocampus (HPC) is essential for many tasks of memory, spatial navigation, and learning, calcium imaging of large populations of HPC neurons can provide new insight on cell changes and organization over time during these tasks. To our knowledge, all reported HPC in vivo calcium imaging experiments have been done in mouse. However, rats have many behavioral and physiological experimental advantages over mice, and, due to their larger size, rats are able to support larger implants, thereby enabling the recording of a greater number of cells. In this paper, we present the first in vivo calcium imaging from CA1 hippocampus in freely moving rats. Using GCaMP7c and the UCLA Miniscope, we demonstrate that hundreds of cells (mean 240+-90 cells per session, maximum 428 cells) can reliably be visualized and held across weeks, and that calcium events in these cells are correlated with periods of movement. We additionally show proof of method by showing that an extremely high percent of place cells (82.3%+-8.1%, far surpassing the percent seen during mouse calcium imaging) can be recorded on a navigational task, and that these place cells enable accurately decoding of animal position. Finally, we show that calcium imaging is rats is not prone to photobleaching during hour-long recordings and that cells can be reliably recorded for an hour or more per session. A detailed protocol for this technique, including notes on the numerous parameter changes needed to use Ca2+ in rats, is included in the Materials and Methods section, and implications of these advancements are discussed.