Hello Adam,

Your jade plant looks healthy, the leaves look firm and green.  Although jade plants are very hardy, there are several conditions that can lead to leaf drop in them.  These include drainage; jades are succulent plants and require very good drainage.  Proper watering is very important with jade plants.  Jade plants also require direct sunlight or supplemental artificial light.  Finally, heat can cause jade plants to lose leaves. 

To ensure correct drainage first check the pot size - there should be at least an inch of soil around the jade plant's roots.  When you water, water should drain from the bottom of the pot.  If it drains right away the root ball may be compressed.  If your plant needs more space replant into a larger pot with good drainage holes; a succulent mix is a good choice for potting soil. 

Since jade plants are succulents they should dry out completely between  waterings, up to 10-14 days between.  If any parts of the plant (leaves, stems, etc) are mushy it's getting too much water.  If the leaves wilt, it's not getting enough water.  You can also check the roots, they should be white and firm.  If the roots are rotted you will need to replace the plant.  You can propagate a new jade plant from a healthy leaf on your plant.  Propagating Jade Plants from Gardeningknowhow.com tells you how.

Jade plants need plenty of light and do well in a sunny window.  You can also add artificial light if needed.

Heat can cause jade plants to lose leaves, especially older leaves.  Moving the plant to an area with good air movement and/or lower temperatures can help the plant.

This article from UBC Jade plant losing leaves and branches is a good discussion on this topic.