Persons were included as enrolled in school if they were reported as attending or enrolled in a "regular" school or college at any time between February 1, 1960, and the time of enumeration. According to census definition, "regular" schooling refers to formal education obtained in public or private (denominational and nondenominational) kindergartens, elementary schools, high schools, colleges, universities, or professional schools, whether day or night school, and whether attendance was full time or part time; that is, "regular" schooling is that which may advance a person toward an elementary school certificate or high school diploma, or a college, university, or professional degree. Schooling that was not obtained in a regular school and schooling from a tutor or through correspondence courses were counted only if the credits obtained were regarded as transferable to a school in the regular school system. Persons who had been enrolled in a regular school since February 1, 1960, but who had not actually attended, for example, because of illness, were counted as enrolled in school.

Persons were excluded from the enrollment figures if the only schools they had been attending at any time since February 1, 1960, were not "regular" (unless courses taken at such schools could have been counted for credit at a regular school). Schooling which is generally regarded as not "regular" includes that which is given in nursery schools, in specialized vocational, trade, or business schools, in on-the-job training, and through correspondence courses.

Persons who were enrolled were classified according to the level and year of school in which they were enrolled. The levels of school which have been separately identified in this report are kindergarten, elementary school, high school, and college. In most of the tables data are shown for specific grades or years within each level above kindergarten. Elementary school, as defined here, includes grades 1 to 8, and high school includes grades 9 to 12. At the time of enumeration, if a person was attending a junior high school, the equivalent grade in terms of 8 years of elementary school and 4 years of high school was recorded. The term college includes junior or community colleges, regular 4-year colleges, and graduate or professional schools. "Freshman" refers to a person enrolled in the first academic year of school, "sophomore" to a person in his second academic year, "junior" to a person enrolled in his third year, "senior" to a person in the fourth year, and "graduate or professional" to a person in the fifth or higher year of college.

In tables 3 to 7, enrolled persons are classified according to their relative progress in school, that is, according to whether the grade or year in which they were enrolled was below, at, or above the modal, or typical, grades for persons of their age. Inspection of age-grade relationships suggested that, for each age, two consecutive grades were almost equally representative of the mode. Tabulations of the categories "below mode for age," "mode for age and above mode for age" were made for single ages and then combined for publication into the age groupings shown in the tables.
The table below shows the basis used for classifying combinations of age and grade or year in which enrolled into the categories used in this report depicting relative progress in school.

Age	Year in which enrolled
	Below mode for age	Mode for age	Above mode for age
	Elementary:	Elementary:	Elementary:
7	None	1 and 2	3 or higher
8	1	2 and 3	4 or higher
9	2 or lower	3 and 4	5 or higher
10	3 or lower	4 and 5	6 or higher
11	4 or lower	5 and 6	7 or higher
12	5 or lower	6 and 7	8 or higher
			High school:
13	6 or lower	7 and 8	1 or higher
14	7 or lower	Elem. 8 and H.S. 1	2 or higher
		High school:
15	8 or lower	1 and 2	3 or higher
	High school:
16	1 or lower	2 and 3	4 or higher
			College:
17	2 or lower	3 and 4	1 or higher
18	3 or lower	H.S. 4 and College 1	2 or higher
19	4 or lower	College 1 and 2	3 or higher

All college students were enumerated in the 1960 and 1950 Censuses where they lived while attending college whereas, in earlier censuses, unmarried students generally were enumerated at their parental home. Since most colleges are located in nonfarm (primarily urban) areas, the rules for enumerating college students are especially relevant in the interpretation of enrollment data according to residence classifications. A study conducted in the Current Population Survey showed, however, that residence while attending college is the same under both the current and previous procedures for roughly one-half of the college students (e.g., for those who had set up their own households and those living with their parents while attending college); furthermore, only part of the one-half who would be classified at different residences would be counted in different regions or in different urban and rural residence areas.

Persons who were enrolled in school were classified as attending a public or private school. In General, a "public" school is defined as any school which is controlled and supported primarily by a local, State, or Federal governmental agency, whereas "private" schools are defined as schools which are controlled and supported by private persons or organizations, including those supported by a religious organization.

The corresponding question on schooling in the 1910, 1920, and 1930 Censuses Generally applied to a somewhat longer period, the period since the preceding September 1. The 1920 Census was taken in January, however, whereas the 1910 and later censuses were taken in April. In censuses prior to 1940, the question was not restricted as to the kind of school the person was attending. In 1940, the question referred to the period since the preceding March 1. There were indications following that census that in some areas the schools closed early (i.e., before March 1) for such reasons as lack of funds, flood conditions, or crop sowing. For such areas, the enrollment rates would, therefore, have been relatively low. In order to insure more complete comparability among areas, it was considered advisable in 1950 to change the reference period to that between February 1 (the usual date for beginning the second semester) and the time of enumeration. The corresponding reference period was used in 1960.

In 1950, separate questions on highest grade attended and completion of the grade were used for the first time to get data on Years of School Completed instead of the single question on highest grade completed used in 1940. This change probably helped to reduce overreporting of grade in which enrolled. In 1940, the responses to the question on highest grade of school completed were combined with the responses to the question on enrollment, and enrolled persons were assumed to have been enrolled in the grade above the one they had completed. Since there are some indications that many persons in 1960 reported the highest grade attended instead of the highest one completed, there probably was a significant amount of overreporting of year of school in which enrolled in that census.

Also, in 1950, for the first time in a decennial census, kindergarten enrollment was separately identified, but the number of children enrolled in kindergarten was not included with the 1950 statistics on enrollment in regular schools. By 1960, kindergartens had become widely accepted and more than half of the children of kindergarten age not enrolled in elementary school were enrolled in kindergarten. Consequently, in the 1960 statistics, kindergarten enrollment was included with the regular enrollment figures.

The age range for which enrollment data have been asked has varied for the several censuses. Information on enrollment was recorded for persons of all ages in 1910 through 1940, for persons 5 to 29 years old in 1950, and for those 5 to 34 years old in 1960. Most of the published enrollment figures related, however, to ages 6 to 20 in 1910, 7 to 20 in 1920, 5 to 20 in 1930, 5 to 24 in 1940, 5 to 29 in 1950, and 5 to 34 in 1960. The enrollment statistics at the older ages reported in 1930 and 1940 were regarded as of poor quality and as relating mostly to enrollment in other than regular schools. The extended age coverage for the published enrollment data in the recent censuses reflects the increasing number of persons in their late 20's and early 30's who are attending regular colleges and universities.

In 1960, as in prior censuses, persons for whom there was no report on school enrollment were allocated as either enrolled or not enrolled. In both 1940 and 1950, the Editing rules were determined largely on the basis of information on ages of compulsory school attendance as compiled by the U.S. Office of Education. Additional information used in Editing included other items on the schedule and results of Current Population Surveys showing the percent enrolled at various age groups. In General, in 1940 and 1950, persons 5 through 17 years of age not reporting on school enrollment were treated as enrolled, whereas those over 17 years old were considered not enrolled. The General scheme used in eliminating non- responses in 1960 is discussed in the section below on "Collection and processing of data."

Comparisons between the April 1960 Census and the Current Population Survey taken in October 1959, the beginning of the same school year, showed that the figures on public school enrollment in kindergarten through the 12th grade were in close agreement. There were 35.3 million persons enrolled according to the census, compared with 34.9 million according to the October 1959 survey. College enrollment was about 12 percent lower in the census than in the survey. An inquiry made of a sample of colleges and universities showed, however, that nearly all of the differences could be accounted for by attrition in college enrollment between the fall and spring, rather than from undercounting of college students in the census.
Enrollment by age differed somewhat between the two sources. Most of this difference could be explained by shifts in age distribution between the fall and spring; for example, the enrollment rate for persons 18 and 19 years old was higher in the census because many high school seniors who were 17 and 18 years old in October became 18 or 19 in April, before they completed high school.

Data on school enrollment are also collected and published by other Federal, State, and local governmental agencies, and by independent research organizations. This information is generally obtained from reports of school systems and institutions of higher learning, and from other surveys and censuses. These data are only roughly comparable with data collected by the Bureau of the Census by household canvassing, however, because of differences in definitions, subject matter covered, time references, and enumeration methods. To illustrate, the enrollment figures from the census tend to be lower than those in the Biennial Survey of Education, conducted by the U.S. Office of Education, largely because the census data refer to a shorter time period and count a person only once, although he may have attended more than one school during the reporting period. In the biennial survey, some persons are included in the enrollment figures more than once, such as those enrolled in both public and private schools and those enrolled in two different States at any time during the school year. The census data also are unlike enrollment data from other sources in that they are a unique source of national information about the characteristics of enrolled persons and their families.