Single-use plastics are a major contributor to the generation of plastic waste. Biodegradable polymers provide some hope of curbing this emerging waste issue, with polylactic acid being a promising example. This study examined the biodegradation of l-poly(lactic acid)-PLLA, d-poly(lactic acid)-PDLA, various blends of PLLA and PDLA, as well as a sample of sc-PLLA/PDLA-50-50-A annealed for 30 min to induce crystallization. A simulated study in a lab-scale direct measurement respirometer compared the abiotic and biotic degradations of the various films in compost. The films' crystallinity increased at the beginning of degradation before plateauing. The molecular weight (