Treatment systems, methods, and apparatuses for improving the appearance of skin or other target regions are described. Aspects of the technology are directed to improving the appearance of skin by tightening the skin, improving skin tone or texture, eliminating or reducing wrinkles, increasing skin smoothness, or improving the appearance sites with cellulite. Treatments can include cooling a surface of a patient's skin and detecting freezing in the cooled skin. The tissue can be cooled after the freeze event is detected so to maintain the frozen state of the tissue to improve the appearance of the treatment site.