Privately owned business assets are an important source of wealth for families across the world, but measurement issues are believed to hamper our understanding of these firms. We use income and valuations of private firms in the Survey of Consumer Finances (SCF), first validating the data against external aggregates and then using these data to find rates of return for private firms. With the exception of the years leading up to the Global Financial Crisis, overall rates of return on public firms have generally outpaced rates of return on private firms during the past 30 years.