National Coalition of Community-Based Heritage Language Programs - http://www.heritagelanguageschools.org
Heritage Languages Special Interest Group (SIG) of the American Council on the Teaching of Foreign Languages (www.actfl.org)
HLXchange.com – workshops and resources
Start at https://www.nhlrc.ucla.edu/nhlrc/about and then explore Resources, Professional Development, Events, Research, etc.
Heritage Language Learner Assessment bibliography: https://aelrc.georgetown.edu/resources/evaluation/heritage-eval-assess/