In the 1960s, the ideal curriculum, as seen from recommendations in journals and reports, and the implemented curriculum, as viewed from textbooks, referred very little to applications of mathematics outside the subject. Yet today the teaching of real-world applications of mathematics is seen as a necessary component of a good mathematics education. A number of factors are responsible for this change: changing enrollment trends; changing theories toward how students learn and what they can learn; the arrivals of computers and calculators in schools; the public perception of performance of students on standardized tests; and recommendations of business and industry regarding what they would like to see in the people they hire. The change is manifested in various ways beyond the inclusion of problems that relate mathematics to the world outside the classroom. The most widely used of the newer curricula develops important application ideas from basic principles over many years. Newer influences on the thinking of mathematics educators come from advances in applied mathematics that have resulted in major changes in the workplace and a corresponding desire that no students be excluded from significant applied mathematics. As a result, some of the more recent curricula include entire courses based on units, each with a particular application theme, with the expectation that students will work both individually and in groups.