Molecular thin films are intensely studied in connection with applications in chemical recognition, molecular patterning and manipulation, molecular electronics and as tribological films to modify friction and adhesion in nano- and micro-scale devices. I will present studies aimed at understanding the relation between structure, mechanical stability and electronic properties of molecular films. Our studies reveal the strong interdependence between structure and properties and the role of externally applied pressure. Examples include Self-assembled and Langmuir-Blodgett films made of molecules with saturated alkane chains, aromatic and unsaturated bonds, oligothiophenes, etc.