Bread products: This includes cakes, pasta and most baked goods. Put any of these items in your compost pile, and you've rolled out the welcome mat for unwanted pests.
Cooking oil: Smells like food to animal and insect visitors. It can also upset the compost's moisture balance.
Diseased plants: Trash them, instead. You don't want to transfer fungal or bacterial problems to whatever ends up growing in your finished compost.
Heavily coated or printed paper: This is a long list, including magazines, catalogs, printed cards and most printed or metallic wrapping paper. Foils don't break down, and you don't need a bunch of exotic printing chemicals in your compost.
Human or animal feces: Too much of a health risk. This includes kitty litter. Waste and bedding from non-carnivorous pets should be fine.
Meat products: This includes bones, blood, fish and animal fats. Another pest magnet.
Milk products: Refrain from composting milk, cheese, yogurt and cream. While they'll certainly degrade, they are attractive to pests.
Rice: Cooked rice is unusually fertile breeding ground for the kinds of bacteria that you don't want in your pile. Raw rice attracts varmints.
Sawdust: So tempting. But unless you know the wood it came from was untreated, stay away.
Stubborn garden plants: Dandelions, ivy and kudzu are examples of plants or weeds which will probably regard your compost heap as a great place to grow, rather than decompose.
Used personal products: Tampons, diapers and items soiled in human blood or fluids are a health risk.
Walnuts: These contain juglone, a natural aromatic compound toxic to some plants.
Aerosol cans: Sure, they're metal. But since spray cans also contain propellants and chemicals, most municipal systems treat them as hazardous material.
Batteries: These are generally handled separately from both regular trash and curbside recycling.
Brightly dyed paper: Strong paper dyes work just like that red sock in your white laundry.
Ceramics and pottery: This includes things such as coffee mugs. You may be able to use these in the garden.
Diapers: It is not commercially feasible to reclaim the paper and plastic in disposable diapers.
Hazardous waste: This includes household chemicals, motor oil, antifreeze and other liquid coolants. Motor oil is recyclable, but it is usually handled separately from household items. Find out how your community handles hazardous materials before you need those services.
Household glass: Window panes, mirrors, light bulbs and tableware are impractical to recycle. Bottles and jars are usually fine. Compact fluorescent lightbulbs (CFLs) are recyclable, but contain a small amount of mercury and shouldn't be treated as common household bulbs. For ideas on how to handle them, see 5 ways to dispose of old CFLs.
Juice boxes and other coated cardboard drink containers. Some manufacturers have begun producing recyclable containers. These will be specially marked. The rest are not suitable for reprocessing.
Medical waste: Syringes, tubing, scalpels and other biohazards should be disposed as such.
Napkins and paper towels: Discouraged because of what they may have absorbed. Consider composting.
Pizza boxes: Too much grease. While some compost enthusiasts steer clear of adding pizza box cardboard to their pile, others report no problems. It's that or the trash.
Plastic bags and plastic wrap: If possible, clean and reuse the bags. Make sure neither gets into the environment.
Plastic-coated boxes, plastic food boxes, or plastic without recycling marks: Dispose of safely.
Plastic screw-on tops: Dispose separately from recyclable plastic bottles. Remember that smaller caps are a choking hazard.
Styrofoam: See if your community has a special facility for this.
Tires: Many states require separate disposal of tires (and collect a fee at the point of sale for that purpose).
Tyvek shipping envelopes: These are the kind used by the post office and overnight delivery companies.
Wet paper: In general, recyclers take a pass on paper items that have been exposed to water. The fibers may be damaged, and there are contamination risks.