capitalisation

Writers are frequently confused about when to capitalise words such as mum and dad. It isn’t as complicated as it may seem. The general principles are as follows:

If you are using the word in place of their name, you should capitalise:

I'm cooking dinner for Mom
She asked Dad to mow the lawn
"Oh no," said Grandma

This applies if you are using the word as a title as part of their name:

We went to visit Uncle Gareth
"I've got things to do," said Grandpa Joe

If you are using the word as a label – a description of relationship or kinship – you should not capitalise:

I'm cooking dinner for my mom
Jenny's grandmother plays tennis
He looks just like his brother

You can usually tell if you need a capital letter by substituting a proper name and deciding if it sounds strange:

I told Mother the cat ran away 
I told Helen the cat ran away

I told my Mother the cat ran away
I told my Helen the cat ran away
I told my mother the cat ran away

This isn’t foolproof because people do say ‘my Helen’ or ‘our Helen’ to distinguish between multiple Helens or to imply relation. However, the use of a possessive pronoun (my, your, his, her, our or their) is often a good indicator that you should not capitalise.

This is my second post on capitalisation (the first one was on capitalising months and seasons), and it is an expanded answer to Erik Porter’s question about whether to capitalise mom in the phrase my mom. I hope it helps!

I know some writers find it hard to use capital letters correctly; New Hart’s Rules has an introduction to capitalisation you might find reassuring:

Capital letters in English are used to punctuate sentences, to distinguish proper nouns from other words, for emphasis, and in headings and work titles. It is impossible to lay down absolute rules for all aspects of capitalisation … the capitalisation of a particular word will depend on its role in the sentence, and also to some extent on a writer’s personal taste or on the house style being followed.

The most important thing, I think, is to consider why you have used a capital letter – nouns don’t automatically need one.

There are some general principles you can use to guide you. The convention for months and seasons is fairly simple. I have included days and festivals below because they are often queried at the same time.

Days

The names of days are capitalised:

She was born on a Wednesday
Can I visit next Saturday?

Months

The names of months are capitalised:

The referendum will be held on 23 June 2016
I'm going on holiday in April

Seasons

The names of seasons are not capitalised:

I like to visit the beach in summer
There was a distinct lack of snow this winter

However, you should use a capital letter if you have personified the season:

And Winter shook his frosty mane
The warm sun ended Spring's slumber

Festivals and holidays:

The names of festivals, holy days and holidays are capitalised:

We are preparing for Ramadan
I don't like Halloween
What are you doing on May Day?

If you would like more information on using capitals, I recommend starting with Trask’s Guide to Punctuation. If you would like additional guidance, New Hart’s Rules is a useful style guide for UK publishing and is fairly thorough on the topic on capitalisation.

References:

New Hart’s rules: the handbook of style for writers and editors (2014) 2nd edn. Oxford: Oxford University Press.

Trask, R. L. (1997) The Penguin guide to punctuation. London: Penguin Books.