The zygomycete Blakeslea trispora produces high amounts of the general zygomycete β-carotene-derived sexual signal compounds, the trisporoids. These can be isolated from the culture medium and purified by extraction with organic solvents followed by thin layer chromatography. Concentration is determined spectrophotometrically using specific extinction coefficients established for some members of this compound family. The effect of the extraction and activity of the isolated compounds is best tested physiologically, exploiting the ability of trisporoids to induce the formation of sexually committed hyphae, the zygophores, in other zygomycete species. Methods for B. trispora culture, trisporoid extraction, and further analyses of trisporoids are described in this chapter.