The　success　of　information　technology　has　clearly　demonstrated　that　miniaturization　often　leads　to　unprecedented　performance,　and　unanticipated　applications.　This　hypothesis　of　＂smaller-is-better＂　has　motivated　optical　engineers　to　build　various　nanophotonic　devices,　although　an　understanding　leading　to　fundamental　scaling　behavior　for　this　new　class　of　devices　is　missing.　Here　we　analyze　scaling　laws　for　optoelectronic　devices　operating　at　micro　and　nanometer　length-scale.　We　show　that　optoelectronic　device　performance　scales　non-monotonically　with　device　length　due　to　the　various　device　tradeoffs,　and　analyze　how　both　optical　and　electrical　constrains　influence　device　power　consumption　and　operating　speed.　Specifically,　we　investigate　the　direct　influence　of　scaling　on　the　performance　of　four　classes　of　photonic　devices,　namely　laser　sources,　electro-optic　modulators,　photodetectors,　and　all-optical　switches　based　on　three　types　of　optical　resonators;　microring,　Fabry-Perot　cavity,　and　plasmonic　metal　nanoparticle.　Results　show　that　while　microrings　and　Fabry-Perot　cavities　can　outperform　plasmonic　cavities　at　larger　length-scales,　they　stop　working　when　the　device　length　drops　below　100　nanometers,　due　to　insufficient　functionality　such　as　feedback　(laser),　index-modulation　(modulator),　absorption　(detector)　or　field　density　(optical　switch).　Our　results　provide　a　detailed　understanding　of　the　limits　of　nanophotonics,　towards　establishing　an　opto-electronics　roadmap,　akin　to　the　International　Technology　Roadmap　for　Semiconductors.