The objective of this thesis was to study reactivity of self-assembled monolayers (SAMs) in different chemical reactions. These reactions ranged from covalent coupling via nucleophilic substitutions (i.e. base-catalyzed hydrolysis and aminolysis of SAMs of N-hydroxysuccinimide (NHS) ester disulfides) and coordination chemistry, to supramolecular host-guest interactions. The hydrolysis and aminolysis of NHS-C10 SAMs on gold surfaces were monitored on the nanometer scale by a novel approach termed “inverted” chemical force (iCFM). SAMs served as model systems to study interfacial reactivity and to quantify the impact of packing constraints, steric effects and differences in mechanism on reaction kinetics. The obtained knowledge was then applied in micro- and nanofabrication via area-selective deposition of reactive molecules. Functionalization and patterning of reactive surfaces were obtained by means of microcontact printing (mCP) and AFM based approaches, such as dip-pen nanolithography (DPN). In particular, the pattering of SAMs of b-cyclodextrins, which possess molecular cavities as specific recognition sites to anchor other molecules via specific and directional supramolecular interactions, was achieved by means of mCP and (DPN). In addition poly(amidoamine) (PAMAM) dendrimers were covalently linked to reactive SAMs via amide bond formation and the patterning of these SAMs with PAMAM dendrimers, in the micro and nanometer scale by means of mCP and DPN, was studied.