This note draws from an emergingliterature on firm informality as well as data collected onmicro enterprises and informal firms as part of the WorldBank’s enterprise survey initiative for Kenya. The purposeof the note is to assess the main constraints facinginformal firms, identify patterns of productivity and firmdynamics, and better understand drivers for formalization.Section one provides an overview of key characteristics andmain investment climate constraints facing informal firms.In section two, patterns of informal firm finance areexplored, while in sections three and four, laborproductivity and drivers of firm growth are analyzed.Section five examines incentives to remain informal andpolicies that can catalyze formalization. This is followedby a conclusion. Due to the sampling methodology used, allresults pertain to the sample of surveyed firms; hence, duecaution is necessary in extrapolating the results to thebroader informal sector in Kenya. Nevertheless, theassessment of the surveyed firms could provide importantinformation on identifying policies as well as firm-levelsupport that could boost productivity and catalyzeformalization. This could have important implications foreconomic growth and job creation in Kenya.