TL;DR. Byron Sharp's How Brands Grow (2010) and the Ehrenberg-Bass Institute's decades of research settle a question most of marketing still argues about: brands grow by getting more buyers, not by making existing ones more loyal. Growth is a penetration story. Loyalty is roughly fixed by the double jeopardy law, so the levers that move the needle are market penetration, mental availability, distinctive assets, and category entry points. This guide walks through the laws, what they mean, and what they ask of your strategy. It is the boring stuff that works — and it is the thesis of this site.
How do brands actually grow?
They grow by adding buyers. That is the single most replicated finding in marketing science, and it is the foundation of How Brands Grow (Sharp, 2010). Bigger brands have many more buyers than smaller brands; but those buyers are only slightly more loyal. When brands grow, market penetration rises and loyalty barely moves. When they decline, penetration falls and loyalty, again, barely shifts.
This is the double jeopardy law: smaller brands get hit twice — they have fewer buyers and slightly less loyal ones. It is why the Dirichlet model (Goodhardt, Ehrenberg & Chatfield) can predict a brand's penetration, frequency, and share from its market share alone, with striking accuracy. The model works because loyalty does not vary much across brands. That is not an opinion; it is a pattern that has held across hundreds of categories and dozens of countries for sixty years.
The strategic consequence is uncomfortable for much of marketing orthodoxy. If growth comes from penetration — more buyers — then loyalty programmes and CRM have a low growth ceiling. Your heaviest buyers already buy you as much as the category allows; reaching them more efficiently defends revenue but does not grow the brand. Growth requires reaching the light buyers and non-buyers who represent the untapped ceiling. Reach matters more than precision for growth. Narrow targeting to high-intent segments optimises conversion but caps penetration.
What are mental availability and distinctive assets?
If penetration is the goal, mental availability is the mechanism. Jenni Romaniuk and Byron Sharp (How Brands Grow 2, 2016) define mental availability as the probability that a buyer thinks of your brand in a buying situation. It is not the same as awareness — a buyer can be aware of your brand and never think of it when it matters. Mental availability is about being cued by the situations in which people buy.
Mental availability is built by linking your brand to many buying situations — what Romaniuk calls category entry points — and by making the brand instantly recognisable through distinctive assets. Distinctive assets are the non-brand-name elements that identify your brand: colours, logos, typefaces, characters, slogans, shapes, sounds. Their job is not to "differentiate" your brand on a rational benefit; it is to make the brand easy to notice and remember, so that advertising deposits into the right memory.
This reframes a lot of marketing practice. It is not enough to be differentiated; you must be noticed, linked to buying situations, and easy to recall. A brand with strong mental availability is simply more likely to be in a buyer's consideration set when a need arises — and in categories where most buyers are not in the market right now, that is almost the entire game.
What is the 95:5 rule for B2B?
The 95:5 rule, from Ehrenberg-Bass research on B2B buyer behaviour (John et al.), holds that at any given moment only about 5% of potential B2B buyers are in-market — actively shopping. The other 95% are out-market: not buying today, but they will buy someday.
This overturns the default B2B playbook. Most B2B marketing is demand capture — lead generation, gated content, intent data, lead scoring — and every step of it assumes the target is in-market. That is rational for the 5%, but it has a structural ceiling: it can only ever reach the small, finite, heavily contested pool of people who are actively shopping, while every competitor targets the same 5% with the same intent data.
The 95% are invisible to that playbook. They do not trigger intent signals or fill out forms. But they are forming the consideration set right now, through advertising exposure and category experience. When a triggering event finally arrives — a budget cycle opens, a contract expires — the brands that come to mind first are the ones that built mental availability while the buyer was still in the 95%. If your brand is not in a buyer's mind before they enter the market, you face an uphill battle to get in — because by then they are part of the 5%, and the competition is already there.
The lesson generalises beyond B2B. Any category with a long purchase cycle — cars, insurance, mortgages, appliances — shows the same in/out-market dynamic on a shorter timescale. Reach future buyers before they are shopping, or lose them to the brands that did.
What are category entry points?
Category entry points (CEPs), developed by Romaniuk & Sharp (How Brands Grow 2, 2016), are the thoughts, situations, and needs that cue a buyer to enter a category. If you ask people what comes to mind for "fast food," some think "cheap lunch," others "hangover food," others "kids' birthday treat," others "road trip." Each of those is a category entry point — a door into the category.
The evidence shows that brands grow by being linked to more category entry points, not by owning a single one more deeply. A brand linked to many buying situations has more chances to be thought of, so it has higher mental availability and, in turn, higher penetration. The competitive question is not "what is our unique position?" but "how many of the category's entry points are we connected to, and how strongly?"
In practice this means your advertising should build many distinct memory links — between the brand and the range of situations in which the category is bought — rather than hammering one message at one segment. It also means measuring CEPs: ask category buyers what comes to mind for a given situation, and track whether your brand is among the answers. It is a more honest growth metric than most of what fills a brand tracker.
What does this mean for your strategy?
The laws of brand growth add up to a coherent, and deliberately unglamorous, playbook:
- Make penetration your primary growth metric. Track the percentage of category buyers who buy you in a period. Use buyer panel data, continuous tracking, or — as a leading indicator — share of search.
- Prioritise broad reach over narrow targeting for growth. Your objective is to reach non-buyers and light buyers. Use mass-reach channels; aim for the whole category, not just high-value segments.
- Build mental availability, not just awareness. Link your brand to many category entry points and invest in distinctive assets so non-buyers can recognise and recall you when a buying moment arises.
- Don't neglect physical availability. Penetration also depends on being easy to buy — distribution, shelf presence, search visibility, convenience. Mental availability without physical availability is wasted.
- Expect loyalty to stay roughly flat as you grow. This is not failure; it is the double jeopardy law at work. If loyalty is not soaring while penetration rises, you are growing exactly the way the evidence predicts.
- Reach the 95% before they shop. In B2B and any long-cycle category, brand advertising to out-market buyers is not a luxury — it is the source of future demand.
The common thread: growth is about being thought of by more people, in more buying situations, and being easy to buy when the moment comes. Loyalty programmes, CRM, and personalisation have their place, but they are maintenance, not growth. If you want to grow, raise penetration.
Where do marketers go wrong with brand growth?
- "Growth means more loyal customers." The evidence says growth means more customers (higher penetration), with loyalty nearly constant. This is the most replicated finding in marketing science — and the most resisted.
- "The Pareto principle means I should focus on my top 20%." Your heaviest buyers already buy at near-maximum frequency. Growth comes from the other 80% — the light and non-buyers.
- "Differentiation is what drives growth." In most categories, brands are perceived as remarkably similar. What separates growing brands is stronger mental availability and distinctive assets, not sharper rational differentiation.
- "Penetration and market share are the same." They are correlated but distinct. Penetration is a headcount; share is a wallet measure. Confusing them leads to poor diagnosis.
- "Loyalty programmes are my growth engine." They defend the base and can shift metrics at the margin — but they cannot grow the business meaningfully against a law-like ceiling.
Doesn't loyalty matter at all?
It matters, but less than most marketers assume — and not in the way they think. The evidence does not say loyalty is irrelevant; it says loyalty is roughly constant across brands of different sizes. Bigger brands have more buyers, and those buyers are slightly more loyal, but the difference is small. This is why trying to grow by deepening loyalty is pushing against a law-like ceiling. The practical takeaway is not "ignore your customers" — it is "don't mistake retention for growth." Defend the base, but build the brand for penetration if you want the business to get bigger.
What if my brand is a niche or premium brand?
The same laws apply. Niche brands are niche because they have low penetration; they grow — when they do — by widening penetration within or beyond their niche, not by squeezing more loyalty from their existing base. A premium brand can have modest penetration but strong share if its few buyers spend heavily. But the growth lever is still penetration: more buyers, however light. The double jeopardy law does not grant exceptions for premium positioning.
How is this different from traditional positioning and differentiation?
Traditional positioning asks brands to find a unique, differentiated place in the mind. The Ehrenberg-Bass evidence is sceptical of differentiation as a growth driver: in most categories, brands are perceived as remarkably similar, and buyers are famously disloyal. What separates growing brands is not sharper differentiation but stronger mental availability and distinctive assets — being noticed, remembered, and linked to more buying situations. You still need a clear, consistent brand. But the objective shifts from "own a unique idea" to "be easy to buy, for more people, in more moments."
Where can I read more about the evidence?
The primary texts are Sharp's How Brands Grow (2010) and Romaniuk & Sharp's How Brands Grow 2 (2016), plus the Ehrenberg-Bass Institute's ongoing publications. For a deeper, critical look at the book and its implications, see our How Brands Grow review.
Key takeaways
- Growth = penetration. Brands grow by getting more buyers, not more loyal ones. Loyalty is roughly fixed.
- Double jeopardy is a law, not a suggestion. Smaller brands get fewer buyers and slightly less loyalty.
- Mental availability is the mechanism. Build it with distinctive assets and many category entry points.
- The 95:5 rule reframes B2B. Most buyers are out-market; reach them before they shop, or lose them.
- Reach > precision for growth. Broad reach to non-buyers is the growth lever; targeting heavy buyers is defence.
Further reading
- Physical availability — why being easy to buy is as important as being easy to think of
- Our review of How Brands Grow — the short version: what the book claims, what it proves, who should read it
- Market Penetration — the metric that actually moves when brands grow.
- Double Jeopardy Law — why smaller brands get hit twice.
- Mental Availability — being thought of in buying situations.
- Distinctive Assets — the assets that make a brand easy to notice and remember.
- The 95:5 Rule — why 95% of B2B buyers are out-market.
- Category Entry Points — the doors into a category.
- How Brands Grow review — our critical look at the book.
Sources & further reading
- Sharp, B. (2010). How Brands Grow. Oxford University Press — the foundational text on penetration, double jeopardy, and mental availability.
- Romaniuk, J. & Sharp, B. (2016). How Brands Grow 2. Oxford University Press — category entry points and distinctive assets.
- Ehrenberg, A. — decades of work on the Dirichlet model, double jeopardy, and the statistical laws of buying behaviour.
- Goodhardt, G., Ehrenberg, A. & Chatfield, C. — the Dirichlet model of buying behaviour.
- John et al. (Ehrenberg-Bass Institute) — research on B2B buyer behaviour and the 95:5 rule.
- Binet, L. & Field, P. (2013). The Long and the Short of It. IPA — the long-term brand case that complements penetration-led growth.
Type: pillar. Reviewed: 2026-07-09. Written by Andrei Tarnovski for Boringly Effective. The boring stuff that works.