THE ARTICLE · 7 MIN
The Lean Startup is a best-selling business book about building new products and companies when nobody knows yet what will work. Here are its big ideas in our own words, a check of its claims and stories against later research and the record, and a few small practices drawn from the parts that hold up.
About the book
The Lean Startup: How Today’s Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses is by Eric Ries, who co-founded IMVU, his third startup, and served as its chief technology officer, and who later became an entrepreneur-in-residence at Harvard Business School. Crown Business published it on 13 September 2011. Before the book he wrote a blog, Startup Lessons Learned, where he first put forward the term “lean startup” in September 2008. It is a practical business book for founders and for people building something new inside established companies, whom Ries calls entrepreneurs too.
We did not read the full book. We read the publisher’s excerpt of chapter 1, the Dropbox section that Ries published in TechCrunch, short passages through Open Library’s search-inside tool, Ries’s blog posts, Steve Blank’s accounts of where the method came from, and the studies behind each claim: the abstracts of all of them, the full text of the 2024 replication, and the revenue section of the 2020 trial.
The big ideas
1. A startup is defined by uncertainty, not size
Ries defines a startup as “a human institution designed to create a new product or service under conditions of extreme uncertainty.” On that definition a team inside a large company can be a startup too, and building one is a discipline that can be managed; in his words, “entrepreneurship is management.”
2. Progress is what you learn
Instead of measuring a new venture by what it ships, the book measures it by validated learning: evidence, from experiments with real customers, about which parts of the plan are right. Ries takes the stance from lean manufacturing, where progress is measured in quality goods; for a startup, he argues, the unit of progress is learning. He describes one company that “achieved failure”: it carried out a plan successfully, faithfully and rigorously, and the plan turned out to be flawed.
3. Build, measure, learn
The core of the method is a feedback loop: turn ideas into products, measure how customers respond, then learn whether to pivot or persevere. Every other process, in the book’s view, should help a team go round that loop faster.
4. The minimum viable product
Ries defines a minimum viable product as the version of a new product that lets a team collect “the maximum amount of validated learning about customers with the least effort”. It does not have to be small: by his account, IMVU’s first one took six months to bring to market. One of the book’s examples is the demo video Dropbox used to gauge interest.
5. Pivot or persevere
When the evidence says a core assumption is wrong, the book’s answer is a pivot: a structural course correction that tests a new fundamental hypothesis, while the overall vision rarely changes. Ries’s own example is IMVU, which, by his account, first built an add-on for existing instant-messaging networks and then found that “our customers did not want an IM add-on; they wanted a stand-alone IM network.”
6. Innovation accounting
To hold a new venture to account, the book proposes “innovation accounting”: learning milestones, and actionable metrics that can show cause and effect. It warns against vanity metrics and what it calls “success theater”, the work a team does to look successful.
7. Small batches and the Five Whys
From lean manufacturing the book also takes working in small batches and the Five Whys, a habit of asking simple questions in turn to find the root cause of a problem.
What holds up
The core of the book, treating a new venture’s plan as a set of hypotheses and testing them, has support from randomised trials in Italy and the UK. Those trials tested a scientific approach to decisions rather than the book’s exact method, and come mostly from one research group. Academic study of the method is young: a 2019 review found the practitioners’ conversation about it largely decoupled from the broader management literature. The book’s origins are well documented, and two of its ideas, the minimum viable product and the Dropbox video, are narrower in Ries’s own telling than they can sound. The rows below give each claim, the verdict and the source.
What the trials tested
The randomised trials did not hand founders a copy of the book. Both groups received training on how to get feedback from the market; the treated group was also taught to build a theory of why its idea would work and to test that theory rigorously, “very much as scientists do in their research”, in the authors’ words. That is close to the book’s spirit and closer still to what its critics recommend. It suggests the hypothesis-testing core of the method changes how founders decide; the effect on revenue was smaller and less certain, and the trials do not, on their own, show that every practice in the book works.
How to use it
These practices come only from the parts that hold up, or partly hold up. They describe; what fits your situation is your call. Nothing here is advice on whether to start a business or spend money on one.
- Writing the plan down as hypotheses. The trials taught founders to build a theory of why their idea would work and test it. The smallest version is writing down the one assumption that would sink the plan if it were false, worded so that a test could show it wrong.
- Testing with the least effort that teaches something. Ries’s own definition of a minimum viable product is about learning per unit of effort, not size. His examples range from Dropbox’s demo video to a simple advertising test that, he wrote, would have revealed how bad one of his concepts was.
- Deciding in advance what would end a project. In the larger set of trials, one clear effect of the training was that more firms dropped ideas that were not promising. Setting, before a test, the result that would end a project is one way to make that call on evidence.
- Pivoting a few times, on purpose. Trained firms tended to make a few radical pivots rather than none or many. Treating a change of direction as a deliberate decision after a test, not a reaction to every setback, matches that pattern.
- Measuring cause and effect. The book separates actionable metrics, which show whether a change caused a result, from vanity metrics. The A/B-testing study links controlled comparisons with start-ups learning faster, both towards products that work and away from ones that do not.
Who it’s for, and who can skip it
It suits founders, product managers and people starting something new inside an established organisation, which the book treats as a startup too. Its scope is set by its own definition: work done under extreme uncertainty. Readers running a well-understood business, or looking for detailed research evidence, will find less here; the book is built on case studies, many drawn from Ries’s own experience and the companies he worked with.
If you liked this
- Deciding under uncertainty, on the pre-mortem, one-way and two-way doors and other decision tools, traced to their sources.
- Mental models checked, including first principles and Goodhart’s law, the warning behind vanity metrics.
- Start with Why, summarised, another business best-seller with its claims checked.
Sources
- E. Ries, The Lean Startup: How Today’s Entrepreneurs Use Continuous Innovation to Create Radically Successful Businesses (Crown Business, 2011): publisher’s page and chapter 1 excerpt; the Dropbox section as published in TechCrunch, 19 October 2011; Open Library search-inside snippets of the Internet Archive copy (2011); The Lean Startup and its principles page.
- E. Ries, “The lean startup”, Startup Lessons Learned, 8 September 2008; “Minimum viable product: a guide”, August 2009.
- S. Blank, “Hear how the Lean Startup began”, 7 July 2015, and his April 2010 posts.
- Hacker News, “My YC app: Dropbox - Throw away your USB drive”, 4 April 2007.
- A. Camuffo, A. Cordova, A. Gambardella and C. Spina, “A scientific approach to entrepreneurial decision making: evidence from a randomized control trial”, Management Science 66 (2020).
- A. Camuffo, A. Gambardella, D. Messinese, E. Novelli, E. Paolucci and C. Spina, “A scientific approach to entrepreneurial decision-making: large-scale replication and extension”, Strategic Management Journal 45 (2024).
- R. Koning, S. Hasan and A. Chatterji, “Experimentation and start-up performance: evidence from A/B testing”, Management Science 68 (2022).
- M. Leatherbee and R. Katila, “The lean startup method: early-stage teams and hypothesis-based probing of business ideas”, Strategic Entrepreneurship Journal 14 (2020).
- T. Felin, A. Gambardella, S. Stern and T. Zenger, “Lean startup and the business model: experimentation revisited”, Long Range Planning 53 (2020); A. Contigiani and D. A. Levinthal, “Situating the construct of lean start-up”, Industrial and Corporate Change 28 (2019).
Checked October 2026. What we read: the publisher’s excerpt of chapter 1 and the Dropbox section published in TechCrunch (not the full book); short search-inside passages of the 2011 printing; Ries’s 2008 and 2009 blog posts and the book’s website; Steve Blank’s two posts; the Hacker News post; the abstracts of every study listed above, the full text of the 2024 replication, and the revenue section of the 2020 trial.
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