Does one parent, one language work?

Often, yes. King and Mackey, in The Bilingual Edge, say one parent, one language (OPOL) is popular and often works. They also say that without deliberate protection of the minority language, a child who understands it but does not speak it is a common result, not a rare one. The method is not the problem. The hours the minority-language parent actually has with the child decide the outcome.

What the method is

Each parent speaks one language to the child, always. One parent speaks the heritage language and the other speaks the community language. The appeal is clarity: the child knows which language belongs to which person.

The method works through exposure. A child learns to speak a language by hearing it, and by using it with someone who answers. OPOL gives the minority language one source of that exposure: one parent.

King and Mackey place Sarah's family in what they call the mixed-language profile: parents with different first languages. For that profile they advise roughly equal quantity and quality of exposure in both languages. Notice the word quantity: a rule about who speaks what says nothing about how many hours each language gets.

How it fails

The community language reaches the child from everywhere else: the street, school, television, friends. The minority language reaches the child through one person. That is the mechanism King and Mackey point to when they recommend extra support for the weaker language inside the home.

Their own case is Sarah, the daughter of Eury and Thorsten, as the book tells it. She understood German perfectly well but insisted on speaking English. She was a "passive" bilingual rather than an "active" one. This is one family's report, and it shows the shape of the problem, not how often it happens. No source read for this site gives a rate.

A second way to fail is a miscount. King and Mackey describe a father who assumed he was doing his part. He turned out to have only 3 to 4 hours a week alone with the child, under 5% of the child's waking hours, as they report it. That explained why the child was not speaking his language.

What to do this week

1. Count the real hours the minority-language parent spends with the child in a week, not the planned ones. The Family Language Audit does this count.
2. Compare the total with the 80% target King and Mackey suggest for the early years (see the article on what 80% looks like in a week).
3. If the hours fall short, add minority-language time with other people: a grandparent, a relative, a caregiver, a class.
4. Give the child reasons to answer in the minority language: a task, a song, a book read together, a person who only speaks it.

The audit shows its one-parent-one-language note only when four things hold: your child's last saved plan says the parents have different first languages, one caregiver is logged as heritage-only and another as community-only, the household is below the 80% line, and only two languages are tracked. It is a pattern check, not a diagnosis: it does not know whether these two caregivers are the child's parents. If the plan says something else, the audit may show a different note that describes the hours only: most hours are in the community language and the heritage hours come from one caregiver. That note does not name the method.

One detail of how the audit counts: a caregiver who switches between both languages, such as a bilingual nanny, counts at half weight. That is real exposure, but less concentrated than a caregiver who speaks only the heritage language.

What is still unknown

• How often OPOL produces a passive bilingual. The book says common, and gives no figure. UNVERIFIED.
• Whether strict separation matters. The book's position, as the repo's notes record it, is that rigid rules matter less than the quantity and quality of input, and that mixing is normal and passes. That is the book's account, not a test of OPOL.
• Whether a child's temperament changes any of this. No source read for this site addresses it for OPOL.

In short: OPOL says who speaks what, not how many hours each language gets. Count the hours the minority-language parent really has, and protect the minority language on purpose rather than trusting the rule to do it.