The human body has been increasing in size in many world-wide populations over at least the past century, according to documented reports. Such increases clearly have implications for the design of automotive equipment. This “secular increase” involves the body as a whole, applies to both men and women, and seems to affect the short-statured more than the tall. Summary estimates for this increase in stature have averaged around 1.0 cm per decade although there may be considerable variability between studies. The most likely explanations for this increase involve improved environmental conditions, specifically better nutrition, health care, and sanitation. Some groups currently show no secular increase in size. These include those who a) live in environments with less than adequate diets and medical care, or b) have already achieved their maximum body size potential as a result of living in optimal environments for growth. The secular increase in size is likely coming to an end. As more people live under more favored environmental conditions which will enable them to achieve maximum growth, the rate of increase will decline. Future changes, at least in technologically developed regions, can be projected at a continually decreasing rate from the former high of about one centimeter per decade.