"A randomized control trial with 432 small and medium enterprises in Mexico shows positive impact of access to 1 year of management consulting services on total factor productivity and return on assets. Owners also had an increase in "entrepreneurial spirit" (an index that measures entrepreneurial confidence and goal setting). Using Mexican social security data, we find a persistent large increase (about 50 percent) in the number of employees and total wage bill even 5 years after the program. We document large heterogeneity in the specific managerial practices that improved as a result of the consulting, with the most prominent being marketing, financial accounting, and long-term business planning."

"Theories of market failures and targeting motivate the promotion of entrepreneurship training programs and generate testable predictions regarding heterogeneous treatment effects from such programs. Using a large randomized evaluation in the United States, we find no strong or lasting effects on those most likely to face credit or human capital constraints, or labor market discrimination. We do find a short-run effect on business ownership for those unemployed at baseline, but this dissipates at longer horizons. Treatment effects on the full sample are also short-term and limited in scope: we do not find effects on business sales, earnings, or employees."

"We document the presence of multiple and varied constraints to small and medium firm growth. This presents both a practical problem for business training programs and a challenge to academic economists trying to identify mechanisms through which these programs may affect outcomes. External validity needs theory. This pushes researchers to narrowly defined and highly selected sample frames, which limits the potential for clear, generalizable policy prescriptions. Ultimately, larger samples, multi-arm evaluations, process documentation, and narrowly-focused, theory-supported empirical work are all needed, but the complexity of the problem limits what we learn from any single study."

"Small businesses are often believed to serve as engines for innovation, employment and social mobility, due to their flexibility in responding to new opportunities and their potential for rapid growth. In developing countries, SMEs make up a particularly large part of the economy, yet data suggests that very few small enterprises in developing countries grow into larger businesses. Researchers conducted a qualitative study of a consulting program in the Philippines designed to help SMEs expand, investigating the obstacles that consultants identified as constraints to firm growth. They found that there is no "one-size-fits-all" approach to business training - most firms have a complex, interconnected set of challenges."