This chapter provides a description of the various oscillating modes of AFM. The oscillating modes described include tapping mode, non-contact mode, and phase imaging. Readers will also find an overview of the key parameters adjusted by AFM operators in order to obtain high-resolution images while using oscillating modes. A discussion of probe characteristics associated with these operating modes is included also. Oscillating modes require the use of a lock-in amplifier, an electronic device that not used in other modes of AFM. For this reason, Chapter 8 provides an overview of lock-in amplifier operation and its role in oscillating modes of AFM. From reading this chapter, readers will also learn how feedback loop operation for oscillating modes differs from contact mode operation. Phase imaging is a technique associated with oscillating modes of AFM allowing AFM operators to obtain images showing material differences on sample surfaces. To allow readers an opportunity to explore this unique technique, a laboratory exercise is included in this chapter involving phase imaging of polymer/metal nanostructures.