Synthesis of methylcyclopentadiene with limited amounts of dimethylcyclopentadiene by-product. Cyclopentadiene monomer is complexed with metallic sodium in diglyme (diethylene glycol dimethylether) and reacted with an alkylating agent such as methyl chloride in the presence of a large stoichiometric excess of cyclopentadiene monomer. A high yield of methylcyclopentadiene is obtained with only a small production of undesirable methylcyclopentadiene. The excess cyclopentadiene is easily recycled in a continuous process.