Attapulgite needle encapsulated with double-layer polymer shell (ATP@DP) were prepared by the soapless seeded emulsion polymerization of the second monomer styrene in the dispersion of the attapulgite needle encapsulated with poly(methyl methacrylate) (ATP@PMMA), which was also conducted by the soapless seeded emulsion polymerization of the first monomer methyl methacrylate with the cetyltrimethylammonium bromide (CTAB) modified attapulgite needle (org-ATP) as seeds. The different morphologies of ATP, ATP@PMMA particles, and ATP@DP particles were characterized by transmission electron microscopy, and the encapsulation mechanism was also discussed. (c) 2007 Wiley Periodicals, Inc.