Search Themes (PMax)

Search Themes are advertiser-provided topic signals in Performance Max campaigns that inform Google’s machine learning about which search queries are relevant to each asset group. They function as directional hints rather than traditional keyword targeting, helping Performance Max enter relevant search auctions faster during the learning phase.

Key Takeaways

• Up to 25 search themes per asset group in Performance Max
• Act as directional signals, not strict keyword targeting — Google may show ads for related queries
• Help Performance Max campaigns ramp up faster by reducing the learning period
• Complement audience signals as an additional input for Google’s targeting AI
• Performance Max will still find queries beyond your search themes through its own discovery

What Are Search Themes

Search Themes were introduced to give advertisers more control over the search component of Performance Max campaigns. Before search themes, Performance Max relied entirely on landing page content and asset text to determine which search queries were relevant. Search themes add an explicit signal layer.

Aspect	Search Themes (PMax)	Keywords (Search Campaigns)
Function	Directional hints for AI	Direct targeting triggers
Match control	No match types	Broad, phrase, exact
Negative control	Limited	Full negative keyword support
Auction entry	One of many signals	Primary trigger
Limit	25 per asset group	Thousands per ad group
Required	Optional	Required

How It Works

Search themes are added within each asset group’s settings:

1. Navigate to your Performance Max campaign and select an asset group
2. Open the Search themes section
3. Enter up to 25 terms or phrases that describe the topics relevant to this asset group
4. Google uses these themes alongside your landing page content, ad assets, and audience signals to determine search query eligibility

Google treats search themes as one input among many. The algorithm may:

• Show ads for queries that closely match your themes
• Expand to related queries it discovers through its own analysis
• Prioritize themes that generate strong performance signals
• De-prioritize themes that do not produce results

Search themes are reported in the Insights tab, where you can see which themes are driving impressions and conversions. The Search Terms Report shows the actual queries matched, though with the same privacy redaction limits that apply to all Performance Max search data.

Practical Example

A commercial cleaning company creates a Performance Max campaign with two asset groups:

Asset Group: “Office Cleaning” Search themes: commercial office cleaning, office janitorial services, corporate cleaning company, workplace sanitization, daily office cleaning service

Asset Group: “Industrial Cleaning” Search themes: warehouse cleaning service, factory floor cleaning, industrial janitorial, manufacturing facility cleaning, post-construction cleanup

Without search themes, Performance Max might take 4-6 weeks to learn which search queries are relevant to each asset group. With well-defined themes:

• Learning period reduced to approximately 2 weeks
• Office cleaning asset group starts appearing for relevant queries within days
• Industrial cleaning assets are correctly matched to industrial queries, not office queries
• Google discovers additional queries like “commercial deep cleaning” and “plant floor maintenance” through its own expansion

Why It Matters

Search themes address one of the biggest advertiser complaints about Performance Max: lack of control over search query targeting. While they do not provide the precision of keyword targeting in Search campaigns, they offer meaningful direction to Performance Max’s AI, particularly during the critical learning phase. For advertisers transitioning from Search campaigns to Performance Max, search themes provide a way to carry over keyword intelligence. Combined with regular review of the Search Terms Report and strategic use of brand exclusions, search themes make Performance Max search targeting more predictable and accountable.