The effect of salt on the filler (PCC) retention using a high molecular weight, high charge density cationic polyacrylamide (CPAM) was studied. Three analytical techniques were combined: Photodispersion analyzer (PDA), focused beam reflectance measurement (FBRM) and derivati/ed polyelectrolytc titration. These three methods enabled the continuous study of the effect of salt on filler (PCC) flocculation from colloidal to larger particle size, as induced by a cationic polyelectrolyte (CPAM). The correlation between PCC flocculation rate and CPAM adsorption dynamics implied a multi-steps flocculation mechanism that challenges the traditional flocculation theory.