On the relationship between sources of within- and between-group differences and measurement invariance in the common factor model Gitta H. Lubke a, * , Conor V. Dolan b , Henk Kelderman c , Gideon J. Mellenbergh d a Graduate School of Education and Information Studies (GSEIS), University of California, Los Angeles (UCLA), Moore Hall, Box 951521, Los Angeles, CA 90095-1521, USA b Developmental Psychology, University of Amsterdam, Amsterdam, The Netherlands c Department of Work and Organizational Psychology, Free University Amsterdam, Amsterdam, The Netherlands d Psychological Methods, University of Amsterdam, Amsterdam, The Netherlands Received 16 January 2001; received in revised form 20 March 2003; accepted 27 March 2003 Abstract Investigating sources of within- and between-group differences and measurement invariance (MI) across groups is fundamental to any meaningful group comparison based on observed test scores. It is shown that by placing certain restrictions on the multigroup confirmatory factor model, it is possible to investigate the hypothesis that within- and between-group differences are due to the same factors. Moreover, the modeling approach clarifies that absence of measurement bias implies common sources of within- and between-group variation. It is shown how the influence of background variables can be incorporated in the model. The advantages of the modeling approach as compared with other commonly used methods for group comparisons is discussed and illustrated by means of an analysis of empirical data. D 2003 Elsevier Science Inc. All rights reserved. Keywords: Common factor model; Within-group differences; Between-group differences; Measurement invariance; Confirmatory factor analysis 0160-2896/03/$ – see front matter D 2003 Elsevier Science Inc. All rights reserved. doi:10.1016/S0160-2896(03)00051-5 * Corresponding author. Tel.: +1-310-206-2053; fax: +1-310-206-6293. E-mail address: glubke@ucla.edu (G.H. Lubke). Intelligence 31 (2003) 543 – 566