www.sciencemag.org SCIENCE VOL 313 29 SEPTEMBER 2006
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EDUCATIONFORUM
M
ontessori education is a 100-year-
old method of schooling that was
first used with impoverished pre-
school children in Rome. The program con-
tinues to grow in popularity. Estimates indi-
cate that more than 5000 schools in the
United States—including 300 public schools
and some high schools—use the Montessori
program. Montessori education is character-
ized by multi-age classrooms, a special set of
educational materials, student-chosen work
in long time blocks, collaboration, the
absence of grades and tests, and individual
and small group instruction in both academic
and social skills (1). The effectiveness of
some of these elements is supported by
research on human learning (2).
We evaluated the social and academic
impact of Montessori education. Children
were studied near the end of the two most
widely implemented levels of Montessori
education: primary (3- to 6-year-olds) and
elementary (6- to 12-year-olds). The Mon-
tessori school we studied [located in Mil-
waukee, Wisconsin (3)], which served
mainly urban minority children, was in its
ninth year of operation and was recognized
by the U.S. branch of the Association
Montessori Internationale (AMI/USA) for
its good implementation of Montessori prin-
ciples (4).
Because it was not feasible to randomly
assign children to experimental and control
educational groups, we designed our study
around the school lottery already in place.
Both the experimental and the control group
had entered the Montessori school lottery;
those who were accepted were assigned to
the experimental (Montessori) group, and
those who were not accepted were assigned
to the control (other education systems)
group. This strategy addressed the concern
that parents who seek to enroll their child in
a Montessori school are different from par-
ents who do not. It is crucial to control for
this potential source of bias, because parents
are the dominant influence on child out-
comes (5).
Recruitment
We contacted parents of children who had
entered the Montessori school lottery in
1997 and 2003 and invited them to be in the
study. All families were offered $100 for
participation.
Because the lottery, which was con-
ducted by the school district, was random,
the Montessori and control groups should
contain similar children. Ninety percent of
consenting parents filled out a demographic
survey. Parents from the Montessori and
control groups had similar average incomes
($20,000 to $50,000 per year) at each stu-
dent age level. This addressed a concern
with a retrospective lottery loser design that
the final samples might be different for rea-
sons other than the treatment. Another vari-
able, ethnicity, was not surveyed because
parent income contributes more to child out-
comes than does ethnicity (6). We were also
concerned that requesting ethnicity data
would reduce participation in this racially
divided city.
Overall, 53 control and 59 Montessori stu-
dents were studied (table S1). The 5-year-old
group included 25 control and 30 Montessori
children, and the 12-year-old group included
28 control and 29 Montessori children.
Gender balance was imperfect, but gender
did not contribute significantly to any of the
differences reported here. Children at the
Montessori school were drawn from all six
classrooms at the primary level and all four at
the upper elementary level. The control chil-
dren were at non-Montessori schools: 27 pub-
lic inner city schools (40 children) and 12
suburban public, private/voucher, or charter
schools (13 children). Many of the public
schools had enacted special programs, such
as gifted and talented curricula, language
immersion, arts, and discovery learning.
Children in both groups were tested for
cognitive/academic and social/behavioral
skills that were selected for importance in
life, not to examine specific expected effects
of Montessori education. Our results
revealed significant advantages for the
Montessori group over the control group for
both age groups.
Results: 5-Year-Olds
Cognitive/Academic Measures. Seven scales
were administered from the Woodcock-John-
son (WJ III) Test Battery (7). Significant dif-
ferences favoring Montessori 5-year-olds were
found on three WJ tests measuring academic
skills related to school readiness: Letter-Word
Identification, Word Attack (phonological de-
coding ability), and Applied Problems (math
skills) (Figure 1). No difference was expected
or found on the Picture Vocabulary test (basic
vocabulary) because vocabulary is highly
related to family background variables (8).
Two WJ tests of basic thinking skills—Spatial
Reasoning and Concept Formation—also
showed no difference.
Five-year-olds were also tested on execu-
tive function, thought to be important to suc-
cess in school. On one such test, children
were asked to sort cards by one rule, switch
to a new rule, and (if they did well) then
switch to a compound rule. Montessori chil-
dren performed significantly better on this
test. A test of children’s ability to delay grat-
ification (a treat) did not indicate statisti-
cally significant differences.
Social/Behavioral Measures. Children were
given five stories about social problems, such
as another child hoarding a swing, and were
asked how they would solve each problem (9).
An analysis of students’ academic and social scores compares a Montessori school with
other elementary school education programs.
Evaluating Montessori Education
Angeline Lillard
1
* and Nicole Else-Quest
2
THE EARLY YEARS
0.4
0.2
0
–0.2
–0.4
Montessori
Mean z score
Control
WJ letter-word
WJ word attack
WJ applied math
Card sort (executive function)
False belief (social cognition)
Refers to justice
Positive shared play
Ambiguous rough play
Results for 5-year-olds. Montessori students ach-
ieved higher scores (converted to average z scores) for
both academic and behavioral tests (18).
1
Department of Psychology, University of Virginia P.O.
Box 400400, Charlottesville, VA 22904, USA.
2
Department
of Psychology, University of Wisconsin, Madison, WI
53202, USA.
*Author for correspondence. E-mail: lillard@virginia.edu
29 SEPTEMBER 2006 VOL 313 SCIENCE www.sciencemag.org
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EDUCATIONFORUM
Montessori children were significantly more
likely (43% versus 18% of responses) to use a
higher level of reasoning by referring to justice
or fairness to convince the other child to relin-
quish the object. Observations at the play-
ground during recess indicated Montessori
children were significantly more likely to be
involved in positive shared peer play and sig-
nificantly less likely to be involved in rough
play that was ambiguous in intent (such as
wrestling without smiling).
The False Belief task was administered to
examine children’s understanding of the
mind (10). Recognition that people repre-
sent the world in subjective as well as objec-
tive ways is a landmark achievement in
social cognition (11). Social negotiation and
discussion about mental states leads to this
advance in children (12). Whereas 80%
(significantly more than chance) of the
Montessori 5-year-olds passed, the control
children were at chance, with 50% passing.
Results: 12-Year-Olds
Cognitive/Academic Measures. Twelve-year-
olds were given 5 minutes to complete a story
beginning “____ had the best/worst day at
school.” The Montessori students’ essays were
rated as significantly more creative and as
using significantly more sophisticated sentence
structures (Figure 2). Control and Montessori
essays were similar in spelling, punctuation,
and grammar. Unlike the 5-year-olds, the 12-
year-olds did not perform differently on the WJ
tests. This is surprising, because early reading
skills normally predict later reading (13). Either
the control group had “caught up” by age 12 to
the Montessori children, or the
12-year-old Montessori chil-
dren were not more advanced in
these early reading skills when
they were 5. If the latter, one
possible explanation is that the
12-year-olds started at the
school when it was in its third
year. The Montessori method
relies on peer teaching and
modeling, so those who are in
the early classes of a new school
lack some advantages relative
to those who begin later.
Social/Behavioral
Measures. As a social skills
test, 12-year-olds read six sto-
ries about social problems
(such as not being asked to a
party) and were asked to
choose among four responses.
Montessori 12-year-olds were
significantly more likely to
choose the positive assertive
response (for example, verbally expressing
one’s hurt feelings to the host). On a question-
naire regarding their feelings about school,
Montessori children indicated having a
greater sense of community, responding more
positively to items like, “Students in my class
really care about each other,” and “Students
in this class treat each other with respect.”
Benefits of Montessori Education
On several dimensions, children at a public
inner city Montessori school had superior
outcomes relative to a sample of Montessori
applicants who, because of a random lottery,
attended other schools. By the end of kinder-
garten, the Montessori children performed
better on standardized tests of reading and
math, engaged in more positive interaction on
the playground, and showed more advanced
social cognition and executive control. They
also showed more concern for fairness and
justice. At the end of elementary school,
Montessori children wrote more creative
essays with more complex sentence struc-
tures, selected more positive responses to
social dilemmas, and reported feeling more
of a sense of community at their school.
These findings were obtained with a lottery
loser design that provides control for parental
influence. Normally parental influence (both
genetic and environmental) dominates over
influences such as current or past school and
day care environments. For example, in the
large National Institute of Child Health and
Human Development (NICHD) study of early
child care, correlations between parenting
quality and WJ early academic tests had effect
sizes comparable to those seen
here, whereas school effects
were much smaller (5). An
evaluation of Success for All,
considered a highly successful
reading intervention, reported
a quarter of a standard devia-
tion as its largest effect size (for
Word Attack) in a randomized
field trial, and stated it was
equal to a 4.69-month advance
in reading skills (14). Stronger
effects are often found in the
first years of pilot programs
when researchers are involved
in implementation of their own
programs (15), termed the
“superrealization effect” (16).
In our study, the school did not
anticipate an evaluation. Esp-
ecially remarkable outcomes
of the Montessori education
are the social effects, which are
generally dominated by the
home environment (17).
Future research could improve on the
research design here by following lottery par-
ticipants prospectively and by tracking those
who drop out and examining their reasons. It
would be useful to replicate these findings in
different Montessori schools, which can vary
widely. The school involved here was affili-
ated with AMI/USA, which has a traditional
and relatively strict implementation. It would
also be useful to know whether certain com-
ponents of Montessori (e.g., the materials, or
the opportunities for collaborative work) are
associated with particular outcomes.
Montessori education has a fundamen-
tally different structure from traditional edu-
cation. At least when strictly implemented,
Montessori education fosters social and aca-
demic skills that are equal or superior to those
fostered by a pool of other types of schools.
References and Notes
1. M. Montessori, The Montessori Method (Schocken,
New York, 1964).
2. A. S. Lillard, Montessori: The Science Behind the Genius
(Oxford Univ. Press, New York, 2005).
3. Milwaukee Public Schools
(http://mpsportal.milwaukee.k12.wi.us/portal/server.pt).
4. Association Montessori Internationale (www.montessori-
ami.org/).
5. NICHD Early Child-Care Research Network, Harvard Ed.
Rev. 74, 1 (2004).
6. G. J. Duncan, W. J. Yeung, J. Brooks-Gunn, J. R. Smith,
Am. Soc. Rev. 63, 406 (1998).
7. K. S. McGrew, R. W. Woodcock, Woodcock-Johnson III
Technical Manual (Riverside Publishing, Itasca, IL, 2001).
8. B. Hart, T. Risley, Meaningful Differences in the Everyday
Experience of Young American Children (P.H. Brookes,
Baltimore, MD, 1995).
11. K. H. Rubin. The social problem solving test-revised
(Univ. of Waterloo, Waterloo, MI, 1988).
12. H. Wimmer, J. Perner, Cognition 13, 103 (1983).
11. C. Zimmer, Science 300, 1079 (2003).
12. J. Amsterlaw, H. Wellman, J. Cogn. Dev. 7, 139 (2006).
13. A. E. Cunningham, K. E. Stanovich, Dev. Psych. 33, 934
(1997).
14. G. D. Borman et al., Am. Ed. Res. J. 42, 673 (2005).
15. M. W. Lipsey, Ann. Am. Acad. Polit. Soc. Sci. 587, 69
(2003).
16. L. J. Cronbach et al., Toward Reform of Program
Evaluation: Aims, Methods, and Institutional
Arrangments (Jossey-Bass, San Francisco, 1980).
17. NICHD Early Child-Care Research Network, Am. Ed. Res. J.
42, 537 (2005).
18. The z-score conversion was used for the graph to give all
tests the same metric. A z score sets the mean (in this
case of the entire sample) at 0, one standard deviation
above the mean at 1.68, and one standard deviation
below the mean at –1.68.
19. Funding was provided by the Jacobs and Cantus
Foundations and sabbatical fellowships from the Cattell
Foundation and the University of Virginia to A.L. J.
DeLoache, B. Detmer, L. Ma, A. Pinkham, R. Tai, and J.
van Reet provided helpful comments, and E. Turkheimer
provided valuable statistical advice. We thank the
Milwaukee schools that participated; the children and
their families; and A. Hart, T. Nishida, A. Pinkham, J van
Reet, and B. Rosen.
Supporting Online Material
www.sciencemag.org/cgi/content/full/[VOL]/[ISSUE]/[PAGE]/DC1
10.1126/science.1132362
0.4
0.3
0.2
0.1
0
–0.1
–0.2
–0.3
–0.4
Montessori
Mean z score
Control
Sophisticated sentence structures
Creative story
Positive social strategies
Sense of school as community
Results for 12-year-olds.
Students in the Montessori pro-
gram wrote more sophisticated
and creative stories and showed
a more developed sense of com-
munity and social skills. Scores
were converted to average
z scores (18).